Final answer:
Stanley Milgram, after his 1960s obedience studies, stated that men are led to kill with little difficulty, demonstrating through his experiments that people are highly likely to follow authority even when it conflicts with their conscience.
Step-by-step explanation:
The individual who stated "Men are led to kill with little difficulty" after conducting obedience studies in the 1960s is D) Stanley Milgram. Milgram was an American social psychologist who conducted one of the most controversial experiments to explore the extent of people's willingness to obey authority figures. The Milgram Experiment demonstrated that nearly two-thirds of participants were willing to deliver what they believed to be lethal shocks to another person, simply because they were instructed to do so by an authority figure.
In Milgram's experiment, the participants were told they were helping in a learning and memory study, instructing them to administer electric shocks to 'learners' who provided incorrect answers. These shocks increased in intensity with each wrong answer, up to 450 volts. However, the subjects were unaware that the 'learners' were actually confederates and that no real shocks were being administered. The results of this study were alarming, showing high levels of obedience to authority that conflicted with the personal conscience of the participants.