The correct option is A True
If we have 3 vectors, →a,→b,→c, then their scalar triple product is given by [→a,→b,→c]=(→a×→b).→c
If →a=→b
then (→a×→b).→c=(→a×→a).→c′
now (→a×→a)=→0 (cross product of 2 identical vectors is zero as angle between them is zero)
So [→a,→b,→c]=0