Find the correct pair of statements
(i) Influx of Cl- into guard cells during stomatal opening is active.
(ii) Entry of sucrose from companion cells into sieve tubes at source involves expenditure of energy
(iii) At the sinks sucrose moves out of phloem by passive transport
(iv) Efflux of `K^(+)` from guard cells during stomatal closure does not involve energy expenditure

Options

A. ii,iv
B. ii,iii
C. `i`,iii
D. iii, iv.

Answer

To solve the question, we need to evaluate each of the four statements provided and determine which pairs are correct. Let's analyze them step by step.

### Step 1: Evaluate Statement (i)
**Statement (i):** Influx of Cl- into guard cells during stomatal opening is active.

- **Analysis:** The influx of chloride ions (Cl-) into guard cells is not the primary mechanism for stomatal opening. Instead, it is the influx of potassium ions (K+) that plays a crucial role. Therefore, this statement is **incorrect**.

### Step 2: Evaluate Statement (ii)
**Statement (ii):** Entry of sucrose from companion cells into sieve tubes at source involves expenditure of energy.

- **Analysis:** The entry of sucrose from companion cells into sieve tubes is indeed an active process. It occurs against the concentration gradient, which requires energy expenditure. Thus, this statement is **correct**.

### Step 3: Evaluate Statement (iii)
**Statement (iii):** At the sinks, sucrose moves out of phloem by passive transport.

- **Analysis:** At the sinks, sucrose typically moves out of the phloem through active transport mechanisms. This is because the concentration of sucrose is often higher in the phloem than in the surrounding cells, necessitating the use of energy to move it out. Therefore, this statement is **incorrect**.

### Step 4: Evaluate Statement (iv)
**Statement (iv):** Efflux of K+ from guard cells during stomatal closure does not involve energy expenditure.

- **Analysis:** The efflux of potassium ions (K+) from guard cells during stomatal closure occurs along the concentration gradient, which means it is a passive process and does not require energy. Thus, this statement is **correct**.

### Conclusion
After evaluating all four statements, we find that:
- **Correct Statements:** (ii) and (iv)
- **Incorrect Statements:** (i) and (iii)

Therefore, the correct pair of statements is **(ii) and (iv)**.

### Final Answer
The correct answer is **(ii) and (iv)**.

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