2. Determine whether the given set under the stated binary operation is or is not a group. If the set and operation form a group, state the identity element of the group. If the set and operation do not form a group, explain how you know. (a) The non-zero real numbers under the operation a b (b) The set fa, b, c,dy under the binary operation o defined by the mulR b bacd tiplication table to the right y (c) The set (7,21,49,63) under the operation of multiplication mod 70.