Simplify the following functions:

$a-(5)F(A,B,C,D)={\displaystyle \underset{?}{\overset{?}{}}}(3,7,11,13,14,15)$

$b-(5)F(A,B,C,D)={\displaystyle \underset{?}{\overset{?}{}}}(3,5,6,7,11),d(A,B,C,D)={\displaystyle \underset{?}{\overset{?}{}}}(4,13,14,15)$

$c-(5)F(A,B,C,D)={\displaystyle \underset{?}{\overset{?}{}}}(6,10,14),d(A,B,C,D)={\displaystyle \underset{?}{\overset{?}{}}}(0,2,8)$