Which research findings below provide the most sound evidence that excessive heat causes greater aggression?

A) Compared to students who took a test in a normal temperature room, test-taking students in a 32ºC room were more likely to express hostility toward a stranger.
B) In cities all over the country, riots are more likely to occur on hot days than on cold days.
C) Throughout the history of the World Series, more batters have been hit by pitched balls on hot days than on cool days.
D) There are fewer riots in Canadian cities than there are in American cities.
E) In Phoenix, drivers without air conditioning are more likely to honk at others than drivers with air conditioning.

A) Compared to students who took a test in a normal temperature room, test-taking students in a 32ºC room were more likely to express hostility toward a stranger.