The ability to roll the tongue upward from the sides is a dominant trait. If a student can roll his/her tongue but one of the parents cannot do so, what does that tell you about the genotype of the other parent?
a) The other parent can roll the tongue.
b) The other parent must be heterozygous or homozygous dominant.
c) The other parent cannot roll the tongue.
d) The other parent must be homozygous recessive.
