The genotypes of a plant variety were TtHh, Tthh, ttHh and tthh, where T = tallness and H= hairy stem. Which one of the following crosses would produce progeny giving a phenotypic ratio approximately 1:1:1:1 ?

Options

A. `TtHhxx TtHh`
B. `TtHhxxTthh`
C. `TtHhxxttHh`
D. `TtHhxxtthh`

Answer

To solve the problem, we need to determine which cross among the given options will produce progeny with a phenotypic ratio of approximately 1:1:1:1 for the traits of tallness (T) and hairy stem (H).

### Step-by-Step Solution:

1. **Identify the Dominant and Recessive Traits**:
- T (tall) is dominant over t (short).
- H (hairy stem) is dominant over h (non-hairy stem).

2. **List the Given Genotypes**:
- The genotypes provided are: TtHh, Tthh, ttHh, and tthh.

3. **Understand the Desired Phenotypic Ratio**:
- A 1:1:1:1 ratio indicates that we want equal proportions of four different phenotypes.

4. **Analyze Each Cross**:
- We will analyze each option provided in the question to see which one yields the desired ratio.

5. **Cross Analysis**:
- **Option A**: TtHH x TtHH
- This cross will yield a phenotypic ratio of 9:3:3:1 (not the desired ratio).
- **Option B**: TtHh x TtHh
- This cross will yield a phenotypic ratio of 9:3:3:1 (not the desired ratio).
- **Option C**: TtHh x ttHh
- This cross will yield a phenotypic ratio of 3:1:3:1 (not the desired ratio).
- **Option D**: TtHh x tt hh
- This cross will yield a phenotypic ratio of 1:1:1:1.

6. **Conclusion**:
- The correct cross that produces a phenotypic ratio of approximately 1:1:1:1 is **Option D**: TtHh x tthh.

### Final Answer:
**Option D** is the correct answer.