The correct option is C None
The sentence is about the noun 'boy' that is modified by the adjective of quality 'good'. A sentence is of a degree of comparison when there are two nouns in comparison. When the qualities of two nouns are the same, then the sentence is of the positive degree. When the quality of one noun is higher than that of the other, the sentence is of the comparative degree. When the quality of one noun is highest, compared to the quality of the others, then the sentence is of the superlative degree. Since the sentence does not have any comparison, as there's only one boy, Tim, and the adjective 'good' does not have a degree of comparison, option D is correct and Options A, B and C are incorrect.