A plant can have green (G) or yellow (g) leaves. It can also have a long (K) or short (k) stem. A scientist is preparing a Punnett square for a dihybrid cross
of a plant with a genotype GGKK. What possible gametes can the plant
produce?
O A. GG, Kk
O B. GK gk
OC. GK, Gk
OD. GK, Gk, gk gk

The correct answer would be gk and gK.
Gamete refers to the haploid germ cell (male or female) which is able to fuse with another gamete of opposite sex of the same species in order to produce zygote.
According to the law of segregation only one copy of the gene (allele) is distributed to each gamete. In addition, it is a random process.
For example, gene Aa would result in the formation of two types of gametes. One will carry A and the other will carry a.
Now, according to the law of independent assortment, alleles of two or more genes are into the gametes independent of each other.
For example, in AABB alleles of gene AA and alleles of BB will be inherited independent of each other.
Now, gametes produced from gg will of only one type that is, g.
Gametes produced by Kk will be of two types which are K and k.
Lastly, all the alleles will be inherited independent of each other which forms two types of gametes. One bearing gK and one bearing gk.