Which Research Findings Below Provide the Soundest Evidence That Excessive

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

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