OE

The clue for the first two blanks is given in the claim that “authors successfully navigated the gray area between simple self-justification and genuine apologia.” “Apologia” means defense, so the authors were defending eating meat. But they did not allow their desire to eat meat to derail their arguments. The first two blanks require something like desires or tendency, and both “proclivity” and “penchant” mean that. “Erudition” (knowledge) is tempting, but it doesn’t fit because saying that someone did not allow his knowledge to drive his arguments is a way of saying that the arguments were bad, and that would not describe the “successful” arguments that won the contest. “Tenacity” (persistence) is also a trap because it looks like tendency. “Salutation” (greeting) and earmark (identifying feature or characteristic) are good GRE vocabulary words but have the wrong meaning. The third blank requires something that can blunt the evils of eating meat, and that goes along with “the eradication of factory farming” and “the return to natural feed,” so you are looking for something that contributes to the well-being of or detracts from the harms done to animals raised for food. “Mitigation of suffering” (easing of suffering) fits this bill. “Effacement of resources” (wiping out of resources) and “imputation of ecology” (blaming of ecology) would both increase harm done to animals and so cannot be correct.