Does each of the following given a function? Include correct reasons for credit.

$($a$)$ Associate with each whole number $n$ its third power $n^3.$

$($b$)$ Assign to the last names of people in town the first names. $($Note: the first names are the inputs, the last names are the outputs$).$

$($c$)$ The ordered pair $(5,2),(7,2),$ and $(4,9).$