Read the following statements and mark the correct option-
(i)Grana lamellae have both PS-I and PS-II.
(ii) ph inside the thylakoid lumen decreases when `H^+` gradient is established across thlakoid membrane
(iii) During reduction of NADP to NADPH + `H^+` protons are removed from thylakoid lumen
(iv) Melvin Calvin used radioctive `14^C in a dicot plant to elucidate path of carbon in biosynthetic phase of photosynthesis.

Options

A. (i) and (iii) are correct
B. (i) and (ii) are correct
C. (i) and (iv) are correct
D. (i) and (ii) are incorrect

Answer

To solve the question, we need to evaluate each of the four statements provided and determine which ones are correct.

### Step-by-Step Solution:

1. **Evaluate Statement (i):**
- **Statement:** Grana lamellae have both PS-I and PS-II.
- **Explanation:** Grana are stacks of thylakoids in chloroplasts where both Photosystem I (PS-I) and Photosystem II (PS-II) are present. This statement is **correct**.

2. **Evaluate Statement (ii):**
- **Statement:** pH inside the thylakoid lumen decreases when H+ gradient is established across the thylakoid membrane.
- **Explanation:** During the light-dependent reactions of photosynthesis, protons (H+) are pumped into the thylakoid lumen, leading to an increase in H+ concentration and a decrease in pH (making it more acidic). This statement is **correct**.

3. **Evaluate Statement (iii):**
- **Statement:** During reduction of NADP to NADPH + H+, protons are removed from the thylakoid lumen.
- **Explanation:** The reduction of NADP+ to NADPH occurs in Photosystem I, but it does not involve the removal of protons from the thylakoid lumen. Instead, NADP+ accepts electrons and protons from the stroma. This statement is **incorrect**.

4. **Evaluate Statement (iv):**
- **Statement:** Melvin Calvin used radioactive 14C in a dicot plant to elucidate the path of carbon in the biosynthetic phase of photosynthesis.
- **Explanation:** Melvin Calvin did use radioactive carbon-14 to study the carbon fixation process, but he primarily conducted his experiments using algae, not specifically dicot plants. Therefore, this statement is **incorrect**.

### Conclusion:
Based on the evaluations:
- **Correct Statements:** (i) and (ii)
- **Incorrect Statements:** (iii) and (iv)

Thus, the correct option is that statements (i) and (ii) are correct.