Let's apply this to Simpson's argument: if the curators have identified only a few contemporary works that they consider high-quality, then the museum should only have a few contemporary works. This is triggered by Simpson's premise, and bridges to the correct conclusion: that the small size of the contemporary collection is appropriate.

Simpson doesn't appeal to the founders’ definition of the museum’s purpose, so this principle can't justify Simpson's argument; it doesn't trigger. Simpson also doesn't claim that there are any works the museum should not have collected, meaning (B) would lead to a conclusion that doesn't match Simpson's argument.

While Simpson does claim that an art museum is unlike an ethnographic one, that isn't a core part of the argument: Simpson's primary claim is that that the contemporary collection is appropriately-sized, because of the curators' beliefs. (C) doesn’t bridge between this premise and conclusion, so doesn't justify the argument.

Simpson’s conclusion is about an art museum, not about an ethnographic museum. Simpson even makes an explicit distinction between ethnographic museums and art museums, so a principle only relating to ethnographic museums just isn't relevant to the argument.

Simpson’s argument is practically the opposite: according to Simpson, the curators’ judgments should determine the size of an art collection. This principle may support a counter-argument, but doesn't justify Simpson's claims.