From Navathe 5E, page 364

A FD $X\rightarrow Y$ in a relation schema R is a **transitive dependency** i__f there is a set of attributes Z that is neither a candidate key nor a subset of any key__ of R and both $X\rightarrow Z$ and $Z\rightarrow Y$ must hold. This implies that Z must be a non-prime attribute.

In, option C and D, it is given that "A prime attribute can be transitively dependent on a key". This means there must exist two FDs like..

1) $KEY\rightarrow NON PRIME$

2) $NON PRIME\rightarrow PRIME$

Here $KEY\rightarrow PRIME$ is transitive dependancy and the intermediate here is non prime because we can only use a non-prime in the intermediate position (by defintion).

Now, These two FDs are in 3NF because LHS of FD1 is superkey and RHS of FD2 is Prime, But it is not in BCNF because LHS of FD2 is not a super key.