Vector →A and →B are mutually perpendicular. Component of →A+→B in the direction of →A−→B will be -
Unit vertor along →A−→B
⇒→A−→B|→A−→B|=→A−→B√A2+B2
So, component of →A+→B along →A−→B
(→A+→B)⋅(→A−→B)√A2+B2=A2−B2√A2+B2
Hence, correct option is option d.