Fecundity in animal world is the maximum possible ability of an individual to produce offsprings during its entire lifetime. Following factors were checked for their effect on fecundity of different animal models,
i. Availabilty of food during breeding season
ii. Mode of fertilization
iii. Population density Which of these factor(s) can regulate fecundity?

Options

A. i,ii
B. ii,iii
C. i, ii, iii
D. None of the above

Explanation

To determine which factors can regulate fecundity in the animal world, we will analyze each of the given factors: availability of food during the breeding season, mode of fertilization, and population density.

### Step-by-Step Solution:

1. **Understanding Fecundity**:
- Fecundity refers to the maximum potential reproductive capacity of an individual, which is the ability to produce offspring throughout its lifetime.

2. **Factor 1: Availability of Food During Breeding Season**:
- Food availability is crucial for energy production. During the breeding season, sufficient food resources can enhance reproductive success by providing the necessary energy for the reproductive processes. Therefore, this factor positively regulates fecundity.

3. **Factor 2: Mode of Fertilization**:
- The mode of fertilization (whether internal or external) can influence the success of reproduction. Different modes may have varying success rates in producing viable offspring. Thus, this factor also plays a role in regulating fecundity.

4. **Factor 3: Population Density**:
- Population density refers to the number of individuals in a given area. High population density can lead to competition for resources, which may reduce the availability of food and space for breeding. Consequently, this can lower fecundity. Conversely, moderate population density may support higher fecundity rates.

5. **Conclusion**:
- All three factors—availability of food during the breeding season, mode of fertilization, and population density—can regulate fecundity in different ways. Therefore, the correct answer is that all three factors are responsible for regulating fecundity.

### Final Answer:
All three factors (1, 2, and 3) can regulate fecundity.

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