This is not a particularly difficult question and what I am about to say was not relevant in this case but I thought it might be worth noting in the off-chance there is ever a similar question. Jo's rule says the most productive programmers must be ALLOWED to work by themselves, not that they must work by themselves. Since the rest of the answer choices are easily consistent, that makes D the correct choice, however it should be noted that there would not be an inconsistency if in the answer choice Yolanda was allowed to work by herself but choose to work with someone else. It is implied that that is not the case with the use of the word assigned, but it is worth noting anyways that her working with someone else is not inconsistent by itself.

I don't understand why you immediately ruled out D when you gave a justification for it in the first minute of the video. As you said, the self-interest of scientists cannot be equated to pursuit of career advancement precisely because self-interest is ambiguously defined. Now, that is not why the conclusion is incorrect but it is why the philosophers premise is invalid.

In contrast answer choice B relies on extremely poor phrasing on the part of the question. Scientists plural is a stand-in for the scientific community, never are individual scientists referred to at all. It would be the same as saying athletes vs community of athletes, we can simply presume that athletes = the whole of athletes because the individual nature isn't specified or even implied at all. It does not say some scientists, all scientists, most scientists, only scientists.