Answer: The correct answer is a. Men administered more painful electric shocks.
Explanation: Multiple researches has been done to establish differences in aggression in regards to gender.
Some studies suggest that men have 20 times more testosterone levels than women and testosterone is linked to aggressive behaviors.
Men tend to engage more in physically aggressive behavior, even at a young age and that can have a biological, psychological and social explanation.
In this case, given what is known about gender differences and agression, it is not surprising that men administered more painful electric shocks.