Assertion :- the third cleavage in frog is latitudinal(horizontal ) .
Reason :- The mitotic spindle orients parallel to the polar axis in each blastomere

Options

A. If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion .
B. If both Assertion and Reason are true but Reason is not correct explanation of the Assertion .
C. If Assertion is true but the Reason is false .
D. If Both Assertion and Reason Are false

Answer

### Step-by-Step Solution:

1. **Understanding Cleavage in Frogs**:
- In frogs, the cleavage of the zygote occurs in a specific pattern. The first cleavage is vertical, leading to two equal cells. The second cleavage is also vertical but occurs at a right angle to the first, resulting in four equal cells.

2. **Identifying the Third Cleavage**:
- The third cleavage in frogs is characterized as latitudinal or horizontal. This means that the division occurs along a horizontal plane rather than vertically.

3. **Role of the Mitotic Spindle**:
- The orientation of the mitotic spindle is crucial in determining the direction of cleavage. In the case of the third cleavage, the mitotic spindle aligns parallel to the polar axis of the zygote.

4. **Conclusion**:
- Since the assertion states that the third cleavage is latitudinal (horizontal) and the reason explains that this is due to the orientation of the mitotic spindle parallel to the polar axis, both the assertion and reason are correct. Therefore, the statement is validated.

### Final Answer:
- Both the assertion and reason are correct: the third cleavage in frogs is latitudinal (horizontal) because the mitotic spindle orients parallel to the polar axis in each blastomere.

---