A soccer competition consisted of two rounds. In each round, the 20 teams competing were divided randomly into 10 pairs, and each pair played a single game. None of the games resulted in a tie, and of the teams that lost in the first round, 7 also lost in the second round. How many teams won both of their games?
(A) 3
(B) 4
(C) 5
(D) 6
(E) 7
Answer: E
Source: Manhattan GMAT