I would say that it`s A`s fault. There is enough, and were enough space for 3 cars. C car was going for the gap that looked possible, B should also given some more room, but it`s totally A`s fault since he saw the car pass, but still desided to go up in the track. A purely idiotioc movie, and made everyone crash. If he hadn`t done that I belive that car C would pass them both. A should go lower in the corner when he saw C was on his side, and it`s better to go low in the corners too, C was very optimistic, but it would be possible if A hadn`t cuted up in his line.