$2\mathrm{.}9$ Derive a minimum sum$-$of$-$products form for each of the following fully specified functions using a Karnaugh map.

a$.F_1(A,B)={\displaystyle \underset{?}{\overset{?}{}}}m(0,2)$

b$.F_2(A,B,C)=$prodM$(1,2,5,7)$

c$.F_3(A,B,C,D)={\displaystyle \underset{?}{\overset{?}{}}}m(0,2,5,7,8,10,13,15)$