A research study aims to explain how people behave after viewing an advertisement about frozen pizza. The research finds that after viewing the ad, viewers tended to go prepare dinner. The research concludes that viewing the ad makes people want to eat. However, what the research did not consider was that the ad was always only aired around dinner time. This meant that people were going to prepare dinner anyway, regardless of having seen the ad.

Which statement about this research is correct?

The ad is a confounding variable.

The ad has face validity.

The ad has construct validity.

The ad lacks internal validity.

The ad lacks ecological validity.