Roan cattle show codominance for the color of their hair. There are alleles for red hair and white hair. What would you expect a heterozygous roan bull to look like if the trait showed incomplete dominance instead?

It would be pink.

Explanation:

Co dominance is the condition when both there is equal expression of both the alleles. The alleles present in heterozygous condition are able to express themselves.

The red hair and white hair are dominant and recessive trait that express themselves when present in homozygous condition. But when present in heterozygous condition they express themselves equally and result in pink color if it is in incomplete dominance. In case of incomplete dominance the dominant trait is not able to express itself fully.

Thus, the answer is pink.