More carbon-saturated and substantially denser than typical terrestrial worlds, planets dubbed "carbon super-Earths" have long perplexed astrophysicists because such compositionally exotic bodies would not be anticipated to populate ancient galactic halos, where most stars are primitive and metal-poor. A prevailing hypothesis holds that these diamond-layered planets coalesced when two long-established, carbon-enriched planetesimals collided and fused into a single, more massive body. Ramirez has advanced a competing model, however, contending that in quiescent stellar neighborhoods-where the ambient density of planetesimals is so attenuated that binary collisions occur too seldom to generate the observed abundance of carbon super-Earths-these anomalous worlds arise instead through multi-body gravitational capture. She proposes that a planetesimal already locked in a binary pairing constitutes a substantially more gravitationally conspicuous target for a third drifting body or even another binary system. Once this hierarchically nested configuration stabilizes, resonant close approaches among the captured bodies could trigger any two to coalesce into a carbon super-Earth. Ramirez's framework makes a testable prediction: each carbon super-Earth so formed should retain a distant bound companion-a signature that, she notes, has been borne out by radial-velocity observations of numerous such planets in the Kepler-192 system.

1. In the context of Ramirez's alternative model, the phrase "more gravitationally conspicuous target" is employed chiefly to account for why a

A. carbon super-Earth would stand a greater chance of colliding and merging with another planetesimal than would a typical terrestrial world.
B. binary pair of planetesimals would be more apt to encounter other drifting bodies than would the typical carbon super-Earth.
C. binary pair of planetesimals would be more susceptible to gravitational interaction with passing bodies than would a solitary planetesimal.
D. carbon super-Earth would be more liable to gravitationally interact with a binary pair than it would with a solitary third planetesimal.
E. solitary third planetesimal would have a greater probability of encountering a binary pair than it would of encountering a carbon super-Earth.


2. On the basis of the passage, which of the following can properly be concluded regarding carbon super-Earths?

A. They are descended from protoplanetary bodies that are more carbon-saturated and substantially denser than typical terrestrial worlds.
B. They are consuming their nuclear fuel at a rate that exceeds that of other planetary types detected in ancient galactic halos.
C. They predate the majority of other planetary varieties residing within the same stellar neighborhood.
D. They occur with lower frequency in quiescent stellar neighborhoods than do binary-planetesimal pairings.
E. They typically derive from the most ancient planetesimals among those populating old galactic halos.


3. According to the passage, what consideration is offered as a reason to question the hypothesis introduced in the second sentence?

A. A disparity between the incidence of planetesimal mergers in certain quiescent stellar neighborhoods and that in other, comparable quiescent neighborhoods.
B. A disparity between the density and carbon enrichment of carbon super-Earths generated by one formation mechanism and the density and carbon enrichment of those generated by an alternative mechanism.
C. A disparity between the frequency of planetesimal collisions in quiescent stellar neighborhoods and that in dynamically active, high-density stellar neighborhoods.
D. A disparity between the carbon enrichment and density of ancient solitary planetesimals and those properties in carbon super-Earths.
E. A disparity between the rate at which solitary planetesimals collide in certain stellar neighborhoods and the number of carbon super-Earths actually observed in those same neighborhoods.