Irrelevant— the psychologist’s hypothesis is about the general population, not about creative geniuses. Also, we don’t know how adventurousness relates to being a creative genius, so we can't determine if creative geniuses are more or less adventurous than others.

Irrelevant—the psychologist compares the cognitive plasticity of siblings in the same family, finding that first-borns have less cognitive plasticity than their younger siblings. But (B) compares first-born children to other first-borns in different families.

If cognitive plasticity correlates with risk-taking, it becomes more plausible that birth order correlates with adventurousness. This is because birth order now correlates with risk-taking, which causes one to be adventurous.

Irrelevant— like (A), a study on business executives can’t be used to draw inferences about the general population. Also, we don’t know how adventurousness relates to being a business executive, so we can't determine if business executives are more adventurous than others.

Irrelevant— we don’t know how adaptability is connected to cognitive plasticity or adventurousness. But even if they are connected, it’s unclear how (E) would strengthen the argument.