The statement completes as the facial feedback hypothesis. Analysis:

• If you suggest that smiling can make someone feel happier, you are endorsing the facial feedback hypothesis, which posits that facial expressions can influence emotional experience.

• This idea is contrasted with other theories like the James-Lange theory (emotion follows physiological arousal) and cognitive mediational perspectives, but the phrasing of the prompt directly aligns with facial feedback.

• Additional summaries and discussions in science media reinforce that smiling can modestly boost mood via facial feedback, though the effect is small and not a universal cure for mood disorders.