A certain kind of snail can have a right-handed direction of shell coiling (DD or Dd) or left-handed coiling (dd). However, if direction of coiling is due to a protein deposited by the mother in the egg cytoplasm, then a Dd egg-producing snail and a dd sperm-producing snail will have offspring of which genotype(s) and phenotype(s)?
a) 1/2 Dd: 1/2 dd; half right-coiling and half left-coiling
b) 1/2 Dd: 1/2 dd; all right-coiling
c) all Dd; all right-coiling
d) all Dd; half right-coiling and half left-coiling