1. (5) let a ={q, r, s, t) and b= {17, 18, 19, 20}; . determine which of the following are functions. explain why or why not. a. fsa x b, where f-(q,17), (r,18), (s, 19), (s, 20)) b. gsax b, where g - [(q, 17). (s, 19), (t, 18), (r,20)) h a x b, where h = {(q, 17), (r, 20), (s, 19), (t, 20)) c, d. ksbx b, where k ((17,17), (18, 17). (19,20), (20,18)) 1 axa, where l={(q, r), (r, , r), (t, t)} e.