$ those subtances which reduce the rate of transpiration are called transpirants.
! Imbibition causes Osmotic pressure.

Options

A. If both As and R are correct and R is correct explanation of As
B. If both As and R are correct but R is not correct explanation of As
C. If As is correct, R is wrong
D. If both As and R are wrong.

Answer

To solve the assertion-reasoning question, we will analyze both statements step by step.

### Step 1: Analyze the Assertion
The assertion states: "Those substances which reduce the rate of transpiration are called transpirants."

1. **Definition of Transpiration**: Transpiration is the process by which plants lose water, primarily through small openings called stomata. This loss occurs in the form of water vapor.
2. **Understanding Transpirants**: The term "transpirants" refers to factors that increase the rate of transpiration, such as light, temperature, humidity, and atmospheric pressure.
3. **Conclusion on Assertion**: Since the assertion incorrectly defines transpirants as substances that reduce transpiration, it is **false**. The correct term for substances that reduce transpiration is "anti-transpirants."

### Step 2: Analyze the Reasoning
The reasoning states: "Imbibition causes osmotic pressure."

1. **Definition of Imbibition**: Imbibition is the process by which a colloidal substance absorbs water. This is commonly observed in seeds that take up water to initiate germination.
2. **Understanding Osmotic Pressure**: Osmotic pressure is the pressure required to prevent the flow of water across a semi-permeable membrane, which is involved in the process of osmosis.
3. **Relationship Between Imbibition and Osmotic Pressure**: Imbibition does not involve a semi-permeable membrane, and therefore, it does not directly cause osmotic pressure. Instead, imbibition is a physical process of water absorption without the constraints of osmotic pressure.
4. **Conclusion on Reasoning**: Since the reasoning incorrectly states that imbibition causes osmotic pressure, it is also **false**.

### Final Conclusion
Both the assertion and reasoning statements are false. Therefore, the correct answer is that both the assertion and reasoning are false.

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