Which of the following statements is not correct

Options

A. Pyramid of biomass in sea is generally inverted
B. Pyramid of biomass in sea is generally upright
C. Pyramid of energy is always upright.
D. Pyramid of numbers in a grassland ecosystem is upright.

Explanation

To determine which statement is not correct regarding the pyramids of biomass, energy, and numbers in ecosystems, we can analyze each statement one by one.

### Step-by-Step Solution:

1. **Understanding the Pyramid of Biomass in Aquatic Ecosystems**:
- The first statement mentions that the pyramid of biomass in aquatic ecosystems (C) is generally inverted. This is correct because in aquatic ecosystems, the biomass of primary producers (like phytoplankton) is often less than that of the higher trophic levels (like zooplankton and fish). Therefore, this statement is true.

2. **Evaluating the Second Statement**:
- The second statement claims that the pyramid of biomass in C is generally upright. This is incorrect. In aquatic ecosystems, the biomass pyramid is typically inverted, as explained in the first step. Hence, this statement is false.

3. **Analyzing the Pyramid of Energy**:
- The third statement asserts that the pyramid of energy is always upright. This is correct because energy transfer between trophic levels is inefficient, with only about 10% of energy being passed on to the next level. Thus, the energy pyramid remains upright.

4. **Examining the Pyramid of Numbers in Grassland Ecosystems**:
- The fourth statement states that the pyramid of numbers in a grassland ecosystem is upright. This is also correct, as there are generally more producers (like grasses) than consumers (like herbivores) in these ecosystems, leading to an upright pyramid.

### Conclusion:
The statement that is not correct is the second one: "The pyramid of biomass in C is generally upright."