Consider the following statements and select the correct option stating which ones are true (T) and which ones are false (F).
(i) Pyramid of biomass is upright in the forest ecosystem and inverted in the grassland ecosystem.
(ii) Pyramid of numbers is inverted in grassland and upright in aquatic ecosystem.
Pyramid of energy depicts the rate of energy flow or productivity at successive trophic levels .
(iv) Ecological pyramids have no place for detritivores and decomposers though they play an important role in an ecosystem.

Options

A. `{:(i,ii,iii,iv),(F,F,T,T):}`
B. `{:(i,ii,iii,iv),(T,F,T,T):}`
C. `{:(i,ii,iii,iv),(F,T,F,F):}`
D. `{:(i,ii,iii,iv),(T,F,F,T):}`

Answer

To solve the question, we need to evaluate each of the four statements regarding ecological pyramids and determine whether they are true (T) or false (F).

### Step-by-Step Solution:

1. **Evaluate Statement (i)**: "Pyramid of biomass is upright in the forest ecosystem and inverted in the grassland ecosystem."
- **Analysis**: The pyramid of biomass is typically inverted in forest ecosystems due to the large biomass of primary producers (trees) compared to the biomass of herbivores. In grassland ecosystems, the pyramid of biomass is usually upright because the biomass of primary producers (grasses) is greater than that of herbivores.
- **Conclusion**: This statement is **False (F)**.

2. **Evaluate Statement (ii)**: "Pyramid of numbers is inverted in grassland and upright in aquatic ecosystem."
- **Analysis**: The pyramid of numbers can be inverted in certain ecosystems, but in grassland ecosystems, it is generally upright because there are more producers (plants) than herbivores. In aquatic ecosystems, it can also be inverted due to the presence of a few large producers (like phytoplankton) supporting many small consumers (like zooplankton).
- **Conclusion**: This statement is **False (F)**.

3. **Evaluate Statement (iii)**: "Pyramid of energy depicts the rate of energy flow or productivity at successive trophic levels."
- **Analysis**: This statement is true as the pyramid of energy illustrates the amount of energy available at each trophic level, showing how energy decreases as it moves up the food chain.
- **Conclusion**: This statement is **True (T)**.

4. **Evaluate Statement (iv)**: "Ecological pyramids have no place for detritivores and decomposers though they play an important role in an ecosystem."
- **Analysis**: This statement is also true because traditional ecological pyramids (biomass, numbers, and energy) do not typically include detritivores and decomposers, even though they are crucial for nutrient cycling in ecosystems.
- **Conclusion**: This statement is **True (T)**.

### Summary of Results:
- Statement (i): False (F)
- Statement (ii): False (F)
- Statement (iii): True (T)
- Statement (iv): True (T)

### Final Answer:
The correct option is that statements (iii) and (iv) are true, while statements (i) and (ii) are false.