Answer:
| R | R
R | RR | RR
r | Rr | Rr
Step-by-step explanation:
The Punnett square is a square diagram that is used to predict the genotypes of a particular cross or breeding experiment.
At the top of the square you have to put the genetic contribution of one parent and at the leftmost column, the genetic contribution of other parent. And then make the combinations, as follows:
| R | R
R | RR | RR
r | Rr | Rr