The Permutation Formula Can Be Used to Determine Which of the Following

The permutation formula can be used to determine which of the following? A: The number of possible license plates made with three letters and three digits given that repetition is allowed
B: The number of ways of choosing 6 CDs from 20 to bring on vacation
$C$ : The number of ways of choosing a first place winner and a second place winner from 10 finalists

A) $B$ and $C$
B) $A$ and $C$
C) $A$ and B
D) A only
E) Conly