You have a yellow pea, but you do not know if it is heterozygous (Yy) or homozygous. When you perform a test cross to a green recessive pea (yy), you observe that half the offspring have yellow peas and half have green peas. What can you conclude?

a. The original, parental yellow pea plant was homozygous (YY).
b. The original, parental yellow pea plant was heterozygous (Yy).
c. Half of the yellow pea offspring are heterozygous (Yy).
d. All the yellow pea offspring are homozygous (YY).