The set of positive integers under the operation of ordinary multiplication is:
(A) not a monoid (B) not a group
(C) a group (D) an Abelian group
B> Not a group but monoid because the inverse element does not exist as they will not be integers
eg: the multiplicative inverse of 3 will be 1/3 which donot closed under positive integer
Ooh sorry sorry Dharmendra Lodhi