If Neuroscience Makes Progress, Then the Mind Is the Brain

Multiple Choice

If neuroscience makes progress, then the mind is the brain. If the mind is soul-like, then rational thought is inexplicable. If neuroscience does not progress, then the mind is soul- like. If philosophy of mind is vacuous, then the mind is not the brain and rational thought is explicable. So, philosophy of mind is not vacuous.
-Working backward from the conclusion of this argument, which of the following is the most likely justification of the last step of the derivation?

A) Cont
B) MT
C) Taut
D) DS
E) CD