Which of the following statements describe natural extinction ?
(i) Extinctions abetted by human activities
(ii) Slow replacement of existing species
(iii) Also known as background extinction
(iv) A small population is most likely to be extinct
(a) (i) and (ii)
(b) (i), (ii) and (iii)
(c) (ii), (iii) and (iv)
(d) (i), (ii), (iii) and (iv)

Options

A. (i) and (ii)
B. (i), (ii) and (iii)
C. (ii), (iii) and (iv)
D. (i), (ii), (iii) and (iv)

Explanation

To determine which statements describe natural extinction, we will analyze each statement one by one:

1. **Statement (i): Extinctions abetted by human activities**
- This statement refers to anthropogenic (human-caused) extinctions, which are not considered natural extinction. Natural extinction occurs without human influence. Therefore, this statement is **incorrect**.

2. **Statement (ii): Slow replacement of existing species**
- Natural extinction can involve the gradual replacement of existing species over time. This process is part of the natural evolutionary cycle. Thus, this statement is **correct**.

3. **Statement (iii): Also known as background extinction**
- Natural extinction is often referred to as background extinction, which is the standard rate of extinction in Earth's history. Therefore, this statement is **correct**.

4. **Statement (iv): A small population is most likely to be extinct**
- Smaller populations are indeed more vulnerable to extinction due to factors like genetic drift, inbreeding, and environmental changes. Hence, this statement is also **correct**.

Now, summarizing the correctness of the statements:
- Statement (i) is incorrect.
- Statements (ii), (iii), and (iv) are correct.

Based on this analysis, the correct option is:
**(c) (ii), (iii), and (iv)**.