The man who won 3 Grand Slams during 2010 is

Andre Agassi
Rafael Nadal
Roger Federer
Roy Emerson

The correct answer is (c) Roger Federer.

Federer won the Australian Open, Wimbledon, and the US Open in 2010. He was the first man to win three Grand Slams in a year since 2008, when Rafael Nadal won the French Open, Wimbledon, and the US Open.

Andre Agassi won eight Grand Slam singles titles in his career, but none of them were in 2010. Rafael Nadal won the French Open in 2010, but he did not win any other Grand Slams that year. Roy Emerson won 12 Grand Slam singles titles in his career, but none of them were in 2010.