An adjective is a word that modifies (or describes) a noun. It can either come before a noun, or after. When it comes after a noun, it is connected to that noun with the help of a linking verb. For example, 'Lata is brave'. The noun is Lata, who is described as 'brave'. This word is an adjective, that connects to the noun 'Lata' with the help of the linking verb 'is'.
Option A: 'This' is a demonstrative adjective that modifies the noun 'man'. Also, 'stronger' modifies the same noun, 'man'. It's a comparative adjective as it compares two nouns, "man" and "Harry".
Hence options A and C are both correct.
Option B is incorrect because 'man' is a noun. It refers to a person.
Similarly, option D is incorrect because Harry is a noun, it's the name of a person.