Which of the following are necessary for evolution by natural selection to take place?
(i) Offspring resemble their parents more than other individuals in the population.
(ii) Differences among individuals exist and lead to different numbers of successful offspring being produced.
(iii) Individuals adjust their development depending on the enviorment
(iv) Every individual possess enormous fertillity.

Options

A. i and ii
B. ii and iv
C. i,iii and iv
D. iii only

Answer

To determine which statements are necessary for evolution by natural selection to take place, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Evaluate Statement (i)**: "Offspring resemble their parents more than other individuals in the population."
- This statement is true. For natural selection to occur, traits must be heritable. If offspring resemble their parents, it means that advantageous traits can be passed down through generations, allowing for the gradual evolution of the population.

2. **Evaluate Statement (ii)**: "Differences among individuals exist and lead to different numbers of successful offspring being produced."
- This statement is also true. Natural selection relies on variation within a population. Individuals with advantageous traits are more likely to survive and reproduce, leading to a higher number of successful offspring. This variation is crucial for the process of natural selection.

3. **Evaluate Statement (iii)**: "Individuals adjust their development depending on the environment."
- This statement is not necessary for natural selection. While organisms can exhibit phenotypic plasticity (the ability to change in response to environmental conditions), this does not directly contribute to the genetic evolution of a population. Natural selection operates on heritable traits, not on traits that can be adjusted during an individual's lifetime.

4. **Evaluate Statement (iv)**: "Every individual possesses enormous fertility."
- This statement is true. High fertility can lead to more offspring, but it is the individuals with advantageous traits that will have a higher chance of survival and reproduction. Therefore, while fertility is a factor, it is the combination of fitness and heritable traits that drives natural selection.

### Conclusion:
Based on the evaluations:
- Statements (i), (ii), and (iv) are necessary for evolution by natural selection.
- Statement (iii) is not necessary.

Thus, the correct answer is that statements (i), (ii), and (iv) are necessary for evolution by natural selection to take place.