Let →r be a unit vector satisfying →r×→a=→b, where |→a|=√3 and |→b|=√2. Then
A →r=2/3(→a+→a×→b)
B →r=1/3(±→a+→a×→b)
C →r=1/4(±→a+→a×→b)
D →r=2/3(±→a+→a×→b)