Find the correct statement

Options

A. During mitosis, endoplasmic reticulum and nucleolus disappear completely at early prophase
B. Chromosomes are arranged along the equator during prophase of mitosis
C. Chromosome is made up of two sister chromatids at anaphase of mitosis
D. Small disc-shaped structures at the surface of centromeres that appear during metaphase aer kinetochores.

Answer

To find the correct statement regarding mitosis, we will analyze each of the provided statements step by step.

### Step 1: Analyze the First Statement
**Statement:** "During mitosis, endoplasmic reticulum and nucleolus disappear completely at early prophase."
- **Analysis:** This statement is incorrect. The endoplasmic reticulum and nucleolus typically disappear during late prophase and early metaphase, not early prophase.

### Step 2: Analyze the Second Statement
**Statement:** "Chromosomes are arranged along the equator during prophase of mitosis."
- **Analysis:** This statement is also incorrect. Chromosomes align along the equatorial plane during metaphase, not during prophase.

### Step 3: Analyze the Third Statement
**Statement:** "Chromosome is made up of two sister chromatids at prophase of mitosis."
- **Analysis:** This statement is incorrect as well. During prophase, chromosomes are visible as two sister chromatids, but they are not fully separated and are still connected at the centromere. However, the term "sister chromatids" is typically used when referring to the structure after DNA replication, which occurs before prophase.

### Step 4: Analyze the Fourth Statement
**Statement:** "Small disc-shaped structures at the surface of the centromere that appear during metaphase are kinetochore."
- **Analysis:** This statement is correct. The kinetochore is indeed a small disc-shaped structure that forms at the centromere of the chromosome during metaphase and is essential for the attachment of spindle fibers.

### Conclusion
The correct statement among the options provided is:
**"Small disc-shaped structures at the surface of the centromere that appear during metaphase are kinetochore."**

---