The structure to which both chromatids of a chromosome are attached is known as ?

Explanation

### Step-by-Step Solution:

1. **Understanding Chromatids**: A chromosome consists of two identical halves called sister chromatids. These chromatids are formed during the DNA replication process.

2. **Identifying the Structure**: The question asks for the structure that holds these sister chromatids together. This is a crucial part of chromosome structure during cell division.

3. **Defining the Centromere**: The structure that connects both sister chromatids is known as the **centromere**. It is located at the center of the chromosome.

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