Bonus: You cross an AABBCCDD parent with an aabbccdd parent…

Bonus: You cross an AABBCCDD parent with an aabbccdd parent to form a heterozygote AaBbCcDd offspring. If genes A/a and D/d are on the same chromosome, and genes B/b and C/c are on a different chromosome, how many different gametes can be produced by the heterozygote? You may assume that no crossing over occurs between genes A/a and D/d, but crossing over can occur between genes B/b and C/c.