Question

in a four - week trial, 91% of users saw firmer, younger - looking skin.
tonin anti - aging serum
ethos (character)
logos (reason)
pathos (emotion)

Explanation:

The advertisement presents data from a trial (91% of users saw results), which is a form of logical appeal. Logos is about using facts, statistics, and reason to persuade.

Answer:

logos (reason)