The genotype of a plant showing the dominant phenotype can be determined by

Options

A. test cross
B. dihybrid cross
C. pedigree analysis
D. back cross

Explanation

To determine the genotype of a plant showing a dominant phenotype, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Phenotype**:
- Identify that the plant shows a dominant phenotype. For example, if we have a tall plant, the dominant trait here is tallness.

2. **Recognize the Genotype Possibilities**:
- A dominant phenotype can be either homozygous dominant (e.g., TT) or heterozygous (e.g., Tt). In contrast, a recessive phenotype (e.g., tt) is easier to identify since it can only be homozygous recessive.

3. **Perform a Test Cross**:
- To determine the genotype of the dominant phenotype plant, perform a test cross. This involves crossing the tall plant (whose genotype we want to determine) with a plant that has a known recessive genotype (e.g., a short plant, tt).

4. **Analyze the Progeny**:
- Observe the offspring from the test cross:
- If the offspring show a 1:1 ratio of tall to short plants, then the genotype of the tall plant is heterozygous (Tt).
- If all offspring are tall, then the genotype of the tall plant is homozygous dominant (TT).

5. **Conclusion**:
- Based on the results of the test cross, you can determine the genotype of the plant showing the dominant phenotype.

### Final Answer:
The genotype of a plant showing the dominant phenotype can be determined by a **test cross**.

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