A maternal effect can cause the offspring phenotype ratio to depart from that of classic Mendelian inheritance. In a species of snail, the dominant allele N codes for right-handed shell coiling and recessive allele n codes for left-handed shell coiling. If an Nn female with right-handed shell coiling males with an Nn male, what is the shell coiling phenotypic ratio of their offspring?
a. 4 right-handed coil:0, left-handed coil
b. 3. Right-handed coil: 1.left-handed coil
c. 3.bidirectional coil: 1.left-handed coil
d. 0.right-handed coil: 4.left-handed coil