What do the letters inside the grid of a punnett square represent?

The correct answer is - Genotype of the offspring

Explanation:

Punnet square is a diagram which is used to predict and show the genotype of offspring that is produced by a cross between male and female gametes. This approach was given by Reginald C. Punnett.

Each grid have a genotype that can determine the phenotype of offspring. The letters used in to fill these grids can be made up of uppercase letters, lower case letters or both. The allele shown in upper case letters shows that the allele is dominant and the allele which is in lowercase letter is a recessive allele.

Therefore the letters inside the grid of a punnet square represents the genotype of the offsprings.