What defense mechanism is the nurse displaying by talking about tanning dangers while frequently tanning herself?

The nurse is demonstrating substitution as a defense mechanism by discussing the dangers of tanning while continuing to tan herself. Substitution occurs when an individual replaces an unhealthy or undesirable behavior with a tolerable one, often as a way to cope with an internal conflict or contradiction. In this case, the nurse acknowledges the risks associated with tanning, indicating her awareness of the potential harm, yet engages in the activity despite this knowledge. This behavior suggests a conflict between her understanding of tanning's dangers and her personal choices, leading to a reliance on substitute coping mechanisms rather than changing the behavior itself.

This contrasts with the other options: denial would involve refusing to accept the dangers of tanning, projection would imply attributing her own feelings about tanning onto someone else, and repression would suggest an unawareness of the dangers and pushing those feelings out of conscious thought. None of those accurately capture the nurse's dual behavior of acknowledging risks while still tanning, making substitution the most fitting defense mechanism in this situation.