Isobrachial chromosomes are

Options

A. Acrocentric
B. Telocentric
C. Sub- metacentric
D. Metacentric

Answer

To answer the question "Isobrachial chromosomes are," we need to understand what is meant by isobrachial chromosomes and then analyze the given options.

### Step-by-Step Solution:

1. **Definition of Isobrachial Chromosomes**:
- Isobrachial chromosomes are defined as chromosomes in which both arms (the sections of the chromosome on either side of the centromere) are equal in length. This means that the two arms of the chromosome are of the same size.

2. **Analyzing the Options**:
- **Option A: Acrocentric Chromosomes**:
- In acrocentric chromosomes, the centromere is located near one end of the chromosome, resulting in one arm being significantly longer than the other. Therefore, this option cannot be isobrachial.
- **Option B: Telocentric Chromosomes**:
- Telocentric chromosomes have the centromere located at one end of the chromosome, which means that one arm is absent. This also cannot be isobrachial since both arms are not present.
- **Option C: Submetacentric Chromosomes**:
- Submetacentric chromosomes have the centromere located slightly off-center, leading to one arm being longer than the other. Thus, this option also does not fit the definition of isobrachial.
- **Option D: Metacentric Chromosomes**:
- In metacentric chromosomes, the centromere is located exactly in the center, resulting in two arms that are equal in length. This matches the definition of isobrachial chromosomes.

3. **Conclusion**:
- Based on the analysis, the correct answer is that isobrachial chromosomes are **metacentric chromosomes**.

### Final Answer:
Isobrachial chromosomes are **metacentric chromosomes**.