Assertion: The pyramid of biomass in sea is generally inverted.
Reason: The biomass of fishes far exceeds that of phytoplankton.

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 a correct explanation of the assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Explanation

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that the pyramid of biomass in the sea is generally inverted.
- In ecological terms, a pyramid of biomass illustrates the total mass of living matter at each trophic level in an ecosystem. In a typical pyramid, biomass decreases from producers to top consumers. However, in certain ecosystems like marine environments, this can be inverted.

2. **Analyzing the Reason**:
- The reason provided states that the biomass of fishes far exceeds that of phytoplankton.
- Phytoplankton are the primary producers in marine ecosystems, but they are often smaller in size and have a lower total biomass compared to larger consumers like fish.

3. **Connecting Assertion and Reason**:
- In marine ecosystems, the biomass of consumers (like fish) can be greater than that of producers (like phytoplankton) because the consumers are larger and more numerous than the producers.
- This leads to the inversion of the biomass pyramid, where the biomass at higher trophic levels (consumers) exceeds that at lower levels (producers).

4. **Conclusion**:
- Both the assertion and the reason are true.
- The reason accurately explains why the pyramid of biomass in the sea is inverted.

5. **Final Answer**:
- The correct answer is that both the assertion and reason are true, and the reason is the correct explanation for the assertion.