Final answer:
The converse of the statement 'If the moon is full, then the vampires are prowling' is 'If the vampires are prowling, then the moon is full,' which corresponds to option (a).
Step-by-step explanation:
The converse of a conditional statement switches the hypothesis and the conclusion. Given the original statement 'If the moon is full, then the vampires are prowling,' the converse would be 'If the vampires are prowling, then the moon is full.' Therefore, option (a) 'If the vampires are prowling, then the moon is full' is the correct converse of the given statement.