In the case of incomplete dominance, when a black chicken (BB) is crossed with a white chicken (WW), the offspring will exhibit a phenotype that is a blend of the two parent phenotypes.
Since black (BB) and white (WW) are the two phenotypes being crossed, the result of the cross would be heterozygous offspring (BW), which would demonstrate an intermediate phenotype. In this scenario, the expected phenotype of the offspring would be gray.
Therefore, the correct response is:
All gray