The theory where ratio between the number of X_ chromosomes and number of complete sets of autosomes will determine the sex is known as

Options

A. Chromosome theory of sex determination
B. Genic balance theory of sex determination
C. Harmonal balance theory of sex determination
D. environmental sex determination

Answer

To answer the question regarding the theory that determines sex based on the ratio of X chromosomes to the number of complete sets of autosomes, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for the name of the theory that relates the ratio of X chromosomes to autosomes in determining sex.

2. **Identify Key Concepts**:
- X chromosomes: These are sex chromosomes that play a significant role in determining the sex of an individual.
- Autosomes: These are non-sex chromosomes that are present in pairs and contribute to the overall genetic makeup.

3. **Recall the Relevant Theory**: The theory that describes the relationship between the number of X chromosomes and the number of complete sets of autosomes is known as the **Genic Balance Theory**.

4. **Historical Context**: This theory was proposed by **B. Bridged in 1925**. It emphasizes that the sex of an individual is determined by the balance between genes for maleness and femaleness.

5. **Application of the Theory**: According to the Genic Balance Theory:
- If the ratio of X chromosomes to autosomes is less than 0.5, the individual will develop as male.
- If the ratio is 1 or more, the individual will develop as female.
- Ratios between 0.5 and 1 can lead to intersex conditions.

6. **Conclusion**: Therefore, the correct answer to the question is that the theory is known as the **Genic Balance Theory**.

### Final Answer:
The theory where the ratio between the number of X chromosomes and the number of complete sets of autosomes determines the sex is known as the **Genic Balance Theory**.