Study the following statements regarding food chains and select the correct ones.
(i) Removal of 80% tigers from an area resulted in greatly increased growth of vegetation.
(ii) Removal of most of the carnivores resulted in an increased population of deers.
(iii) The lenght of food chains is generally limited to 3-4 trophic levels due to energy loss.
(iv) The lenght of food chains may vary from 2 to 8 trophic levels.

A) i and ii B) ii and iii C) i and iii D) iii and iv

Options

A. I and ii
B. ii and iii
C. I and iii
D. iii and iv

Explanation

To solve the question regarding food chains, we will analyze each statement one by one and determine their correctness.

1. **Statement (i)**: "Removal of 80% tigers from an area resulted in greatly increased growth of vegetation."
- **Analysis**: Tigers are carnivores that prey on herbivores like deer. If 80% of tigers are removed, the population of herbivores (deer) would increase significantly due to reduced predation. This increased herbivore population would lead to overgrazing, which would actually decrease vegetation growth, not increase it. Therefore, this statement is **false**.

2. **Statement (ii)**: "Removal of most of the carnivores resulted in an increased population of deers."
- **Analysis**: As discussed, if most carnivores are removed, the herbivore population (deer) would increase due to less predation. This statement is **true**.

3. **Statement (iii)**: "The length of food chains is generally limited to 3-4 trophic levels due to energy loss."
- **Analysis**: According to the 10% law of energy transfer, energy decreases significantly at each trophic level, leading to fewer organisms being supported at higher levels. This results in food chains typically being limited to 3-4 trophic levels. Therefore, this statement is **true**.

4. **Statement (iv)**: "The length of food chains may vary from 2 to 8 trophic levels."
- **Analysis**: While food chains can vary in length, they are generally limited to 3-4 levels due to energy loss, as mentioned earlier. The claim that they can extend up to 8 levels is not supported by ecological principles. Therefore, this statement is **false**.

**Conclusion**: The correct statements are (ii) and (iii). Thus, the answer is **B) ii and iii**.