Question

Two tall pea plants with yellow and smooth pods are crossed. All of the offspring are tall. Three offspring have smooth pods and one has wrinkled pods. The allele for wrinkled pods
a. must be dominant because the trait does not appear in the parent plants
b. must be recessive because the trait does not appear in the parent plants
c. must be dominant because the trait appears in the parent plants
d. must be recessive because the trait appears in the parent plants
I need help