Children read stories and assigned punishment.
Younger children did not take intention vs accident into account. Older children did.

Conclusion: Younger children, then, do not regard people's intentions as relevant to punishment.

We need to weaken the conclusion. Something that tells us that it may not be true that younger children don't regard intention as relevant.

(A) In interpreting these stories, the listeners had to draw on a relatively mature sense of human psychology in order to tell whether harm was produced intentionally or accidentally.

What does this option tell us? That listeners needed to draw on a mature sense to tell whether harm was done intentionally or accidentally. So it tells us that younger children may not have the maturity that is needed to differentiate whether harm was done intentionally or accidentally. In that case, they could not have taken intention into account even if they did consider it relevant. Hence, the problem may lie in identifying intention. This weakens our conclusion. We cannot necessarily say that younger children don't regard intention as relevant.

(B) In these stories, the severity of the harm produced was clearly stated.

The question is whether intention is taken into account or not. Severity of harm produced is irrelevant.

(C) Younger children are as likely to produce harm unintentionally as are older children.

Irrelevant. We are only interested in how younger children assigned punishments on hearing the stories.

(D) The older children assigned punishment in a way that closely resembled the way adults had assigned punishment in a similar experiment.

Irrelevant. We are only interested in how younger children assigned punishments on hearing the stories.

(E) The younger children assigned punishments that varied according to the severity of the harm done by the agents in the stories.

Our question is whether the younger children took intent into account or not. What else they took into account while assigning punishment is irrelevant.

Answer: A