The same considerations as for the previous question on your first choice apply. In addition you may want to consider the following:

Why it is your second rather than your first choice

Differences from first choice option

Similarities with your first choice option

Your response to being asked by the panel or an individual interviewer to focus more on your second choice rather than your first choice.

Any apparent inconsistencies between your first and second choice departments (for example, the difference between Clerkship and the Security Service).

How close a second choice is it really?