Final answer:
The statement indicating suppression is 'I'd rather not talk about it right now.' as it reflects a conscious decision to avoid the subject.
Step-by-step explanation:
The statement by the 19-year-old client that would indicate the use of the mechanism of "suppression" is "I'd rather not talk about it right now."
Suppression involves the conscious decision to delay paying attention to an emotion or need in order to cope with the present reality. It is different from repression, which is an unconscious process. Suppression can be a useful short-term coping strategy, although it is important for the individual eventually to acknowledge and address the underlying thoughts and feelings.