Man cycles with 34kg stone on head

52-year-old Zhang Xumu, exercises by cycling while balancing two stones weighing 34 kg on his head, grabbing people's attention everywhere he goes. According to him, he started to carry stones to work out since 2002. At first, he just wanted to try it out, and then it became part of his exercise routine. He rides a bicycle ten kilometers a day for thirteen years, getting up at four o'clock in the morning.

When did the man start to carry stones to work out?

A. Since 2002

B. Since 2003

C. Since 2004