A logic circuit implements the following Boolean function:

$f(A,C,D)\frac{?}{b}=ar(A)C+\frac{A}{b}ar(C)D$

It is found that the circuit input combination $A=D=l$ can never occur. Find a simpler expression

in Sums of Products form for $F$ using the proper don't care conditions.

a$.,f(A,C,D)=C+\frac{A}{b}ar(D)$

b$.,f(A,C,D)\frac{?}{b}=ar(A)\frac{+}{b}ar\frac{C}{b}ar(D)$

c$.$ Cannot get a simpler expression

d$.f(A,C,D)\frac{?}{b}=ar(A)C+\frac{A}{b}ar(C)$