When the bark of a tree is removed in a circular fashion all around near its base, it gradually dries up and dies because

1. Removing the bark of a tree in a circular fashion (girdling) removes the phloem tissue, which is located just under the bark. 2. Phloem is responsible for transporting sugars (food/energy produced during photosynthesis in the leaves) downwards to the roots. 3. When the phloem is completely removed around the base, the transport of energy to the roots is cut off. 4. Consequently, the roots are starved of energy needed for their survival and function (including absorption of water and nutrients). 5. This leads to the death of the roots, and subsequently, the entire tree gradually dries up and dies. 6. Option (A) is incorrect because water transport from soil to aerial parts occurs through the xylem, which is located deeper within the wood and is typically not removed with the bark. 7. Options (C) and (D) are less direct causes; while infection can occur or oxygen supply might be affected indirectly over time, the primary and immediate reason for the tree's death in this scenario is the starvation of the roots.