Answer :
D, because if white cattle are rr and red cows are RR, then roan cattle
are Rr. Therefore, a cross of Rr x RR would result in half RR and half
Rr.
SOS:
The answer is Rr x rr!
A roan calf is the heterozygous (Rr) F1 produced by breeding red (RR) and white (rr) cattle. The F2 generation is 1/2 roan, 1/4 red, and 1/4 white.
Hope this helps!