which of the following relations is/are function/s
a) x={(1,2),(-3,4),(-1,7),(5,1)}
b) g={(-3,2),(3,1),(-3,2),(5,7)}
c)h={(6,2),(-2,3),(2,6),(7,2)}
c)y={(2,3),(3,2),(-2,3),(3,-2)}​