How did the study ensure that F1 mice reacted to the scent?

The correct answer highlights the use of a conditioned stimulus to ensure that F1 mice reacted to the scent. In psychological experiments, a conditioned stimulus is a previously neutral stimulus that, after being paired with an unconditioned stimulus, evokes a conditioned response. This means that the researchers would have exposed the F1 mice to a specific scent alongside a stimulus that naturally elicits a response (like a food reward or an unpleasant smell), effectively conditioning the mice to react to the scent in a particular way. By creating this association, the study could measure the reaction of the mice to the scent more accurately.

Utilizing a conditioned stimulus allows researchers to examine learned behaviors and responses, providing insight into the cognitive processing of the mice when exposed to familiar or unfamiliar scents. The conditioning process would enhance the validity of the observed reactions as it establishes a clear link between the scent and the mice's behavioral responses.

Other approaches like observing natural interactions or isolating the mice could impact the generalization of findings and may not reliably demonstrate the specific reactions to the scent as a result of learned behavior. Using a training period with rewards might be effective for motivation but does not specifically denote the learned connection essential in this context.