Answer:
b. Adjectives
Explanation:
In this case, “this” and “that” would be adjectives because they are adding clarity to the nouns.
For example, “this cat”. In that instance, “this” is not functioning as a noun, it is instead specifying which cat the speaker is referring to. You can take “this” or “that” and have it modify any noun, and it would still be an adjective.