Which among the following statement/s is/are INCORRECT?
I. Since the origin and form diversification of earth there were four episodes of extinction.
II. The current rate of extinction is 100 to 1000 times faster than in the pre-human times.
III. Ecologists warn that if the present trend continues, nearly one-fourth of all the species on earth might be wiped out within the next 100 years.

Options

A. I & II
B. II & III
C. I & III
D. I,II & III

Answer

To determine which statements are incorrect, let's analyze each statement one by one.

### Step 1: Analyze Statement I
**Statement I:** "Since the origin and form diversification of earth there were four episodes of extinction."

- This statement is incorrect. In fact, there have been **six major episodes of extinction** in Earth's history. These include:
1. Ordovician-Silurian extinction
2. Late Devonian extinction
3. Permian-Triassic extinction
4. Triassic-Jurassic extinction
5. Cretaceous-Paleogene extinction
6. The current extinction event (often referred to as the sixth mass extinction).

**Hint for Step 1:** Remember the major extinction events in Earth's history to verify the number of episodes.

### Step 2: Analyze Statement II
**Statement II:** "The current rate of extinction is 100 to 1000 times faster than in the pre-human times."

- This statement is correct. Current estimates suggest that the extinction rate is indeed **100 to 1000 times higher** than the natural background rate observed before human influence.

**Hint for Step 2:** Compare current extinction rates with historical rates to assess the validity of this statement.

### Step 3: Analyze Statement III
**Statement III:** "Ecologists warn that if the present trend continues, nearly one-fourth of all the species on earth might be wiped out within the next 100 years."

- This statement is misleading. Ecologists actually warn that if current trends continue, nearly **half of all species** could be wiped out within the next **100 years**. Thus, the statement underestimates the potential impact.

**Hint for Step 3:** Look for the consensus among ecologists regarding species extinction rates to evaluate the accuracy of this statement.

### Conclusion
Based on the analysis:
- **Statement I** is incorrect.
- **Statement II** is correct.
- **Statement III** is incorrect.

Thus, the incorrect statements are **I and III**.

### Final Answer
The incorrect statements are **I and III**.

### Summary of Incorrect Statements
- **I:** Incorrect (there are six episodes of extinction).
- **II:** Correct (current extinction rates are significantly higher).
- **III:** Incorrect (the warning is about potentially half of species being wiped out, not one-fourth).