Which is a study that provided evidence that homophobic attitudes may, in part, result from anxiety ...

Which is a study that provided evidence that homophobic attitudes may, in part, result from anxiety about one's own sexual orientation?
 
  a. a study showing that 80 of homophobic men had visited gay pornographic Internet sites within the last six months, compared to 34 of non-homophobic men
  b. a study showing that 80 of homophobic men had erectile responses while watching two men have sex, compared to 34 of non-homophobic men
  c. a study in which 80 of homophobic men showed similar brain activity to gay men, compared to 34 of non-homophobic men
  d. a study in which 80 of homophobic men showed similar walking patterns to gay men, compared to 34 of non-homophobic men