John, David, George, Edward and Robert were the five competitors in a race yesterday. Angela wants to know the result of the race, but they will only tell her who won out of any pair that she asks about. So far, Angela has been told the following: John beat Edward,
David beat George,
Robert beat Edward,
David beat John.
Which two of the competitors should Angela ask about so that she can deduce who won the race?

a. George and Edward
b. David and Robert
c. George and Robert
d. John and George