@Charlotte41,
If you ask a potential guest a question, because you received an Inquiry or a Request, it is offcourse considered as responding. The sooner you respond, the better it is for your respons rate.
But if it is a Request you must also Accept or Decline it within the time limit (24 hours). Or as a third option (for example when a guest sents an unsuitable Request, clearly not have reading your listing etc..) : ask the guest to withdraw the request within the time-limit.
Best regards,
Emiel