Which of the following are functions and which are relations but not functions from the se...

Which of the following are functions and which are relations but not functions from the set of first components of the ordered pairs to the set of second components?

a. {(Montana, Helena), (Oregon, Salem), (Illinois, Springfield), (Arkansas, Little Rock)}

b. {(Pennsylvania, Philadelphia), (New York, Albany), (New York, Niagara Falls), (Florida, Ft. Lauderdale)}

c. {(x,y) | x resides in Birmingham, Alabama, and x is the mother of y, where y is a U.S. resident}

d. {(1,1), (2,4), (3,9), (4,16)}

e. {(x,y) | x and y are natural numbers and x + y is an even number}