Answer:
The correct answer is option C.
Explanation:
The plant is heterozygous (Yy) for the color of seed and homozygous (rr) for the shape of the seed. For the color of the seed, there are two alleles that will take part in gametes formation are (Y) n (y) while for the shape of seed is have only two recessive alleles (r).
So, by the assortment of (Y) n (r) the first gamete will be (Yr) and an assortment of (y) n (r) second gamete will be (yr).
Thus, the correct answer is option C. Yr and yr only.