Is D correct because it is the only one that addresses both clinical equipose (CE) and theoretical equipose (TE)?
A is wrong because it doesn't discuss CE and TE, and the passage doesn't say that theoretical equipose will make it more likely that physicians will fail their ethical requirement.
B is wrong because it doesn't discuss CE and TE, and the passage isn't arguing that clinical trials can achieve more with clinical equipose, it is just that clinical equipose doesn't unnecessarily restrict the trials.
C is wrong because, while it is supported by the text, does not discuss CE and TE, and thus does not get at the main point.
E is wrong because, while it is supported by the text, does not discuss CE, and thus doesn't get at the main point.