Q. Let * be the binary operation on the rational no. given by a*b = a+b+2ab, which is true ?

I * is commutative

II There is a rational no that is a * - identity

III Every rational no has a * - inverse

A) I only

B) II only

C) I , II only

D) I and III only

E) I II and III

I thought ans is E, but ans is C, can somebody explain ?