Removal of a ring bark from the trunk of a tree eventually kills it because.

Options

A. Water cannot go up
B. Fungi and insects attack exposed parts
C. Food does not travel down and root becomes starved
D. Air blocks the xylem.

Answer

### Step-by-Step Solution:

1. **Understanding Girdling**: The process of removing a ring of bark from a tree is known as girdling. This technique involves cutting away the outer layers of the trunk, which include the bark and some underlying tissues.

2. **Identifying the Layers Affected**: The bark contains important layers such as the phloem, which is responsible for transporting food (sugars produced during photosynthesis) from the leaves to other parts of the tree. The cambium layer, which is responsible for the growth of new cells, is also affected during girdling.

3. **Impact on Nutrient Transport**: When the phloem is removed, the tree is unable to transport the food produced in the leaves down to the roots and other parts of the tree. This leads to a lack of essential nutrients for the tree's survival.

4. **Water Transport**: While the xylem, which transports water from the roots to the leaves, is not directly affected by girdling, the overall health of the tree deteriorates due to the lack of food. Without adequate nutrients, the tree cannot effectively utilize the water it absorbs.

5. **Consequences of Starvation**: As the tree becomes starved of food, it begins to weaken and eventually dies. The inability to transport food leads to a decline in the tree's health, making it susceptible to diseases and environmental stressors.

6. **Conclusion**: The primary reason the tree eventually dies after girdling is that the food cannot travel down due to the removal of the phloem. This starvation ultimately leads to the death of the tree.

### Final Answer:
The removal of a ring of bark from the trunk of a tree eventually kills it because food does not travel down, leading to starvation of the tree.