$7\mathrm{.}18*$ Specify the size of a ROM $($number of words and number of bits per word$)$ that will

accommodate the truth table for the following combinational circuit components:

$($a$)$ a binary multiplier that multiplies two $4$bit binary words,

$($b$)$ a $4$bit adder$$subtractor$,$

$($c$)$ a quadruple two$$to$$one$$line multiplexer with common select and enable inputs, and

$($d$)$ a BCD$$to$$seven$$segment decoder with an enable input.