The problem with (B) is that it misstates the conclusion of the argument. The essayist is arguing that vanity's being the motivation for cloning is not enough of a reason to ban cloning.
The argument here is not about whether forcing children to pursue academic success is or is not objectionable. It is about whether cloning is objectionable.
Note that (B) states, "It supports the conclusion that forcing children to pursue academic success is not objectionable."
Forcing children to pursue academic success is an example used to support the essayist's view that we shouldn't ban cloning because vanity is the motivation.
Notice (D) states, "It supports the ethicist's view that vanity's being the motivation for cloning is not enough of a reason to ban cloning."
Hope this helps! Let us know if you have any other questions.
