In summary, the passage tells us: In a bureaucracy, many people are involved in decision-making. Since no one person has the authority to decide if a project will proceed, risky projects are never undertaken in a bureaucracy.
We are asked to identify the answer choice that makes an assumption that will allow the passage's conclusion to follow logically. We may notice that the missing link in the passage's premises is explicitly connecting only individual decision-making with risky projects. In other words, the correct answer should clarify that when many people are involved in a decision, it cannot be risky.
While they may seem similar at first, (D) and (E) state quite different things.
(D) "The only risky projects undertaken are those for which a single individual has decision-making power." We should recognize "the only" as a phrase that introduces the Sufficient condition. So, (D) is saying: Risky projects are undertaken -> Single individual has decision-making power. The contrapositive of this is: More than one person has decision-making power -> Risky projects are not undertaken. This matches the missing link we identified above and allows the passage to flow logically. Therefore, (D) is correct.
(E) "People sometimes take risks as individuals that they would not take as part of a group." First, we may notice that (E) does not use language that matches the passage as well as the language in (D) does. More importantly though, (E) is different than (D) because of the word "sometimes." We are looking for an answer choice that will clarify that groups can never make risky decisions or that risky decisions are made only by individuals, which (E) does not do. Instead, (E) uses a quantifier, which leaves open the possibility that groups can make risky decisions. Therefore, (E) does not state anything that significantly affects the passage and is incorrect.
Does that make sense? Please let us know if you have any other questions and best of luck with your studies!
