Which of the following represents a test cross?

Options

A. Ww x WW
B. Ww x Ww
C. Ww x ww
D. WW x WW

Answer

To determine which of the given options represents a test cross, we need to understand the definition and purpose of a test cross.

### Step-by-Step Solution:

1. **Understanding Test Cross**:
A test cross is a genetic cross between an individual with an unknown genotype (which may be homozygous dominant or heterozygous) and a homozygous recessive individual. The purpose of a test cross is to determine the genotype of the unknown parent based on the phenotypes of the offspring.

2. **Analyzing the Options**:
We will analyze each option to see if it fits the criteria for a test cross.

- **Option 1**: Capital W small w crosses with Capital W Capital W.
- Here, both parents have dominant traits (one is heterozygous and the other is homozygous dominant). This is not a test cross.

- **Option 2**: Capital W small w crosses with Capital W small w.
- Both parents are heterozygous. This is also not a test cross.

- **Option 3**: Capital W small w crosses with small w small w.
- In this case, one parent is heterozygous (Capital W small w) and the other parent is homozygous recessive (small w small w). This fits the definition of a test cross.

- **Option 4**: Capital W Capital W crosses with Capital W Capital W.
- Both parents are homozygous dominant. This is not a test cross.

3. **Conclusion**:
The only option that represents a test cross is **Option 3: Capital W small w crosses with small w small w**.

### Summary:
The correct answer is **Option 3**.

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