The race is 200 meters long. So we want to look at the graph and see which runner was the first to cover 200 meters.
==> All 3 runners were at the starting line (0 m) when the clock said 0 sec. So nobody jumped out ahead before time=0, and it was a fair start.
==> Runners B and C both arrived at 200 m when the clock said 25 sec.
==> Runner-A arrived at 200 m when the clock said 20 sec. So he was there first, and won the race.