Short Answer 
The response explains the use of a Punnett square to predict genetic combinations, specifically focusing on finding the X-linked genotype for red eyes (X^R Y), which indicates a male offspring with this dominant characteristic. In a 4×4 Punnett square, only 25% of the squares represent the desired outcome, making it crucial to identify the specific configuration within the grid.
Step 1: Understand the Punnett Square
A Punnett square is a grid used to predict genetic combinations from parental alleles. In a 4 x 4 Punnett square, there are a total of 16 squares, each representing a possible genotype of the offspring. In this case, we are particularly interested in one specific genotype combination out of the total squares. With only 25% of the squares representing the desired outcome, we should expect to find that result once among the total options presented.
Step 2: Identify the Dominant Allele
The trait we are examining, red eyes, is a dominant characteristic. This means that it is represented by a capital letter, specifically R. Additionally, since red eyes are X-linked, we must denote this gene’s location on the X chromosome. The focus is on finding offspring that have the genotype X^R Y, which indicates a male offspring with red eyes, as males inherit the Y chromosome from their father.
Step 3: Determine the Desired Genotype Combination
In seeking the X^R Y genotype within the Punnett square, it is vital to locate the specific configuration that allows for this combination. Considering the X-linked nature of the trait, only one square in the entire Punnett square must align with this exact genotype. The referenced attachment illustrates this specific Punnett square, showcasing the desired inheritance pattern effectively.