Let $A=\{3,4,8,9,12,16,18\},$ and let the relation $R$ on $A$ be defined by aRb if and

only if $(a|b$ AND $b>a).$

Then, $R^2$ UNION R$^3=$

a$.\{(3,9),(4,16)\}$

b$.\{(3,18),(4,16)\}$

c$.\{(4,16)\}$

d$.$ None of the Given Choices

e$.\{(4,12),(8,16)\}$

f$.\{(3,9)\}$