Number of onto function from Set A to Set B:
There are 3 elements in set B, all these elements need to be mapped to some element in set A.
For a function to exist every element of the domain has a unique value.
a of Set B can be mapped to any of the 5 elements of Set A
b of Set B can be mapped to any of the other 4 elements in Set A and
c of Set B can be mapped to any of the other 3 elements in Set A
Thus the number of onto functions that can be obtained is 5*4*3=60
Number of onto function from Set B to Set A:
There are 5 elements in Set A whereas there are only 3 elements in Set B, which effectively means only 3 elements of Set A at the max can be mapped to Set B.
For a function to exist every element of the domain has a unique value.
Thus no onto function can be defined from set B to Set A
Correct Answer: None of the above.