- (a) Contrapositive: If not Nicole was born on December 25, then not Nicole was born on Christmas Day.
- (b) Converse: If Nicole was born on December 25, then Nicole was born on Christmas Day.
- (c) Inverse: If not Nicole was born on Christmas Day, then not Nicole was born on December 25.
Thus, the answers are:
\[
\boxed{\text{(a) Contrapositive: If not Nicole was born on December 25, then not Nicole was born on Christmas Day.}}
\]
\[
\boxed{\text{(b) Converse: If Nicole was born on December 25, then Nicole was born on Christmas Day.}}
\]
\[
\boxed{\text{(c) Inverse: If not Nicole was born on Christmas Day, then not Nicole was born on December 25.}}
\]