Topic: Degree of Comparison,

Best Answer Explained in Below-:

The correct choice, "D) of the happiest children in the class," conveys a clear, grammatically correct description of Tehseen's state relative to his peers. This option correctly uses the plural form "children," indicating that Tehseen is one among multiple happy individuals in the class, emphasizing inclusivity and a comparative sense of happiness.

Looking at the other options, we can see why they fall short. Option A, "of the happy child of his class," is incorrect due to the lack of clarity and proper pluralization. It suggests Tehseen is merely one of many happy children but does not convey his level of happiness effectively.

Option B has awkward phrasing, saying, "child who was the happiest of as the classes," which is not only grammatically incorrect but also confusing in its structure.

Option C, "of the happiest child of the class," implies that Tehseen is the only happiest child, which undermines the context of "happiest children."

Thus, Option D stands out as the most accurate and well-structured choice, accurately reflecting Tehseen's happiness while correctly framing him as part of a larger group, enhancing clarity and meaning.