The correct ascending squence with respect to their water potential is
(a) `pi=-0.8 MPa, P=+0.4MPa`
(b) `pi=-1.0 MPa, P=+0.5MPa`
(c) `pi=-0.9 MPa, P=+0.2MPa`
(d) `pi=-0.3 MPa, P=+0.2MPa`

Options

A. a, b, c, d
B. c, b, a, d
C. c, a, b, d
D. c, d, b, a

Answer

To solve the question regarding the correct ascending sequence of water potential from the given options, we need to calculate the water potential (W) for each option using the formula:

\[ W = \pi + P \]

where:
- \( \pi \) = solute potential
- \( P \) = pressure potential

We will calculate the water potential for each option step by step.

### Step 1: Calculate Water Potential for Each Option

1. **Option A**:
- \( \pi = -0.8 \, \text{MPa} \)
- \( P = +0.4 \, \text{MPa} \)
- \( W_A = -0.8 + 0.4 = -0.4 \, \text{MPa} \)

2. **Option B**:
- \( \pi = -1.0 \, \text{MPa} \)
- \( P = +0.5 \, \text{MPa} \)
- \( W_B = -1.0 + 0.5 = -0.5 \, \text{MPa} \)

3. **Option C**:
- \( \pi = -0.9 \, \text{MPa} \)
- \( P = +0.2 \, \text{MPa} \)
- \( W_C = -0.9 + 0.2 = -0.7 \, \text{MPa} \)

4. **Option D**:
- \( \pi = -0.3 \, \text{MPa} \)
- \( P = +0.2 \, \text{MPa} \)
- \( W_D = -0.3 + 0.2 = -0.1 \, \text{MPa} \)

### Step 2: List the Water Potential Values

Now we have the following water potential values:
- \( W_A = -0.4 \, \text{MPa} \)
- \( W_B = -0.5 \, \text{MPa} \)
- \( W_C = -0.7 \, \text{MPa} \)
- \( W_D = -0.1 \, \text{MPa} \)

### Step 3: Arrange in Ascending Order

To find the ascending order of water potential, we compare the calculated values:
- The most negative value indicates the lowest water potential.
- The order from lowest to highest is:
1. \( W_C = -0.7 \, \text{MPa} \) (Option C)
2. \( W_B = -0.5 \, \text{MPa} \) (Option B)
3. \( W_A = -0.4 \, \text{MPa} \) (Option A)
4. \( W_D = -0.1 \, \text{MPa} \) (Option D)

### Step 4: Conclusion

Thus, the correct ascending sequence of water potential is:
- Option C (−0.7 MPa)
- Option B (−0.5 MPa)
- Option A (−0.4 MPa)
- Option D (−0.1 MPa)

### Final Answer

The correct ascending sequence with respect to their water potential is:
- C < B < A < D