In 1986, Roger Clemens Pitched 254 Innings and Finished with a 24-4

In 1986, Roger Clemens pitched 254 innings and finished with a 24-4 record during the regular season. He struck out 238 batters, recorded an earned run average of 2.148 and a WHIP (walks plus hits per inning pitched) of 0.969. He earned $340,000, which converts to $644,998 in 2007 dollars. In 2007, Roger Clemens pitched 99 innings and finished with a record of 6-6 during the regular season. He recorded 68 strikeouts, an ERA of 4.18 and a WHIP of 1.33. He was paid $17,690,413 for the 2007 season. Which of the following is the most likely explanation for the increase in Clemens? salary from 1986 to 2007?

A) The marginal revenue associated with an additional win in baseball increased.
B) The marginal revenue associated with an additional win in baseball decreased.
C) The quantity demanded of baseball players decreased.
D) Clemens' marginal product of labor increased.