According to the Discussion of the History of Research on Mental

According to the discussion of the history of research on mental imagery,

A) the early behaviorists rejected research about mental imagery, but they began to conduct imagery research during the early 1950s.
B) the topic of mental imagery has consistently been more popular in the United States than in Europe.
C) the popularity of mental imagery increased as cognitive psychology became more influential.
D) surprisingly, theorists and researchers did not mention mental imagery until about 1930.