So how do we get chickens with white and black spots? Shouldn’t they be only white or black?

Codominance

Explanation:

This is an example of codominance.

Basically with this type of genetics, both alleles for that trait, in this case feather color, are dominant. This means that both will appear in the phenotype, instead of a dominant phenotype overshadowing a recessive phenotype.

Here, the two dominant alleles are the one that governs white pigment and the one that governs black pigment. Since codominance is occurring, we see a speckled chicken instead of just an entirely white one or an entirely black one.

Hope this helps!

the correct answer is d