The correct option is A →b∣∣∣→b∣∣∣2+→a×→b∣∣∣→a×→b∣∣∣2
We have →a⊥→b
⇒→a,→b,→a×→b are linearly independent, →v can be expressed uniquely in terms of →a,→b and →a×→b
Let →v=x→a+y→b+z(→a×→b) …(1)
Given →a⋅→b=0, →v⋅→a=0, →v⋅→b=1, [→v →a →b]=1
From equation (1),
→v⋅→a=x(→a)2=0
⇒x=0→v⋅→b=x→a⋅→b+y∣∣∣→b∣∣∣2+z→b⋅(→a×→b)=1⇒y∣∣∣→b∣∣∣2=1
⇒y=1∣∣∣→b∣∣∣2
→v⋅(→a×→b)=x⋅0+y⋅0+z∣∣∣→a×→b∣∣∣2=1⇒z=1∣∣∣→a×→b∣∣∣2
∴ From equation (1),
→v=→b∣∣∣→b∣∣∣2+→a×→b∣∣∣→a×→b∣∣∣2