Maths-
General
Easy

Hint:

In this question we have to find the total number of injections from set A to set B, where injection is a mapping (or function) between two sets such that the domain (input) of the mapping consists of all the elements of the first set, the range (output) consists of some subset of the second set, and each element of the first set is mapped to a different element of the second set (one-to-one).