Assertion. A plant girdled upto phloem shows signs of degeneration of lower portion.
Reason. food transportation will stop causing the degeneration of the roots

Options

A. If both are true but reason being correct explanation
B. both true but reason is not correct explanation
C. assertion is true but reason is wrong
D. and both are wrong.

Answer

### Step-by-Step Solution:

1. **Understanding Girdling**: Girdling is a process where a ring of bark, including the phloem, is removed from a tree or plant. This interrupts the transport of nutrients and organic substances.

2. **Role of Phloem**: The phloem is responsible for transporting the products of photosynthesis (mainly sugars) from the leaves to other parts of the plant, including the roots.

3. **Assertion Analysis**: The assertion states that a plant girdled up to the phloem shows signs of degeneration of the lower portion. This is true because, without the phloem, the food produced in the leaves cannot reach the roots, leading to their degeneration.

4. **Reason Analysis**: The reason states that food transportation will stop, causing the degeneration of the roots. This is also true. When the phloem is removed, the transport of food (sugars) to the roots is halted, which results in the roots not receiving the necessary nutrients, leading to their degeneration.

5. **Conclusion**: Both the assertion and the reason are true, and the reason correctly explains the assertion. Therefore, the correct answer is that both statements are true, and the reason is the correct explanation for the assertion.