Given the function

$f(a,b,c,d)=m(0,3,4,5,6,7,8,9,11,13,14,15),$

$($a$)$ List all prime implicants $(1\mathrm{.}0$ points$),$

Answer:

$($b$)$ List only the essential prime implicants, and $(1\mathrm{.}0$ points$)$

Ansi

$($c$)$ Give the minimum SoP expression. $(0\mathrm{.}5$ points$)$