Assertion : Cleavage is also called fractionating process.
Reason : In cleavage, number of blastomeres increases but size of blastomeres decreases.

Options

A. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
B. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
C. If the assertion is true but the reason is false
D. If both the assertion and reason are false

Explanation

To analyze the assertion and reason provided in the question, we can break it down into a step-by-step solution:

### Step 1: Understanding the Assertion
- The assertion states that "Cleavage is also called a fractionating process."
- Cleavage refers to the series of rapid cell divisions that occur after fertilization, leading to the formation of smaller cells called blastomeres.

**Hint:** Remember that cleavage is a process that occurs after fertilization and involves cell division.

### Step 2: Understanding the Reason
- The reason given is that "In cleavage, the number of blastomeres increases but the size of blastomeres decreases."
- During cleavage, the zygote divides mitotically, resulting in an increase in the number of cells (blastomeres) while the overall size of each cell decreases due to the limited cytoplasm being divided among the new cells.

**Hint:** Focus on the characteristics of cleavage and how it affects cell size and number.

### Step 3: Analyzing the Relationship
- Both the assertion and reason are true statements about the process of cleavage.
- The reason explains why cleavage is referred to as a fractionating process: as the number of cells increases, the size of each cell decreases, effectively "fractionating" the original zygote into smaller parts.

**Hint:** Consider how the increase in number and decrease in size relate to the concept of fractionation.

### Step 4: Conclusion
- Since both the assertion and reason are true, and the reason provides a correct explanation for the assertion, we can conclude that the correct option is that both the assertion and reason are true, and the reason is a correct explanation of the assertion.

**Hint:** Look for options that confirm both statements and their relationship.

### Final Answer:
Both the assertion and reason are true, and the reason is a correct explanation of the assertion.