Study the following statements regarding mitochondria and select the correct ones.
These are the sites of aerobic respiration.
(ii) Matrix contains single, circular ds DNA molecule, a few RNA molecules, 70S ribosomes.
(iii) Mitochondria divide by fission.
(iv) Mitrochondria are fully-autonomous.

Options

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

Explanation

To determine which statements regarding mitochondria are correct, let's analyze each statement step by step.

### Step 1: Analyze Statement (i)
**Statement:** "These are the sites of aerobic respiration."

**Explanation:** Mitochondria are indeed known as the powerhouses of the cell because they are the sites where aerobic respiration occurs. This process involves the breakdown of glucose in the presence of oxygen to produce ATP (adenosine triphosphate), carbon dioxide, and water.

**Conclusion:** This statement is **correct**.

### Step 2: Analyze Statement (ii)
**Statement:** "Matrix contains single, circular ds DNA molecule, a few RNA molecules, 70S ribosomes."

**Explanation:** The mitochondrial matrix does contain a single, circular double-stranded DNA molecule, along with some RNA molecules and 70S ribosomes. This is a characteristic feature of mitochondria, which supports the theory that they have evolved from prokaryotic ancestors.

**Conclusion:** This statement is **correct**.

### Step 3: Analyze Statement (iii)
**Statement:** "Mitochondria divide by fission."

**Explanation:** Mitochondria can replicate themselves through a process called fission, which is similar to binary fission seen in bacteria. This allows mitochondria to increase in number within the cell as needed.

**Conclusion:** This statement is **correct**.

### Step 4: Analyze Statement (iv)
**Statement:** "Mitochondria are fully-autonomous."

**Explanation:** Mitochondria are not fully autonomous; they are considered semi-autonomous organelles. While they have their own DNA and can perform some functions independently, they still rely on the nucleus for many proteins and regulatory functions.

**Conclusion:** This statement is **incorrect**.

### Final Conclusion
Based on the analysis:
- Statement (i) is correct.
- Statement (ii) is correct.
- Statement (iii) is correct.
- Statement (iv) is incorrect.

Thus, the correct statements regarding mitochondria are **(i), (ii), and (iii)**.