At metaphase, chromosmes are attached to the spindle fibres by their

Options

A. Satellites
B. Secondary constrictions
C. Kinetochores
D. Centromere

Explanation

To answer the question "At metaphase, chromosomes are attached to the spindle fibres by their:", we will follow these steps:

### Step-by-Step Solution:

1. **Understanding Metaphase**:
- Metaphase is a stage in cell division where chromosomes align at the equatorial plane of the cell, known as the metaphase plate. This arrangement is crucial for the proper segregation of chromosomes during the next phase of cell division.

**Hint**: Remember that during metaphase, chromosomes are not just floating around; they are organized in a specific way.

2. **Role of Spindle Fibers**:
- Spindle fibers are structures that help separate the chromosomes during cell division. They are made up of microtubules and extend from the spindle poles to the chromosomes.

**Hint**: Think about what connects the chromosomes to the spindle apparatus.

3. **Chromosome Structure**:
- Each chromosome has a region called the centromere, which is crucial for the attachment of spindle fibers. The kinetochores are protein complexes that form on the centromere and are the actual sites where spindle fibers attach.

**Hint**: Focus on the specific part of the chromosome that interacts with the spindle fibers.

4. **Identifying the Correct Answer**:
- The question asks how chromosomes are attached to the spindle fibers during metaphase. The attachment occurs at the kinetochores, which are located at the centromere of each chromosome. Therefore, the correct answer is **C. Kinetochores**.

**Hint**: Consider the function of kinetochores in the process of cell division.

### Conclusion:
The correct option is **C. Kinetochores**. During metaphase, chromosomes are attached to the spindle fibers by their kinetochores.