Pinker and Dempsey Drew Different Conclusions on Whether Contemporary International

Pinker and Dempsey drew different conclusions on whether contemporary international relations is more peaceful than it was in the past because

A) one drew on the philosophical tradition while the other used a historical approach.
B) one was a realist while the other was a constructivist.
C) neither used the behavioral approach,which would have led them to reach the same conclusions because of its focus on empirical data.
D) they were examining different data.