Cooking is his hobby.

The underlined word is used as a:

The correct answer is "Gerund".

Key Points

• Let us explore the given options:
  • Verbs are words that show action, occurrence, or state of being. Almost every sentence requires a verb. The basic form of a verb is known as its infinitive.
  • A gerund is a noun made from a verb by adding "-ing". We can use a gerund as the subject, the complement, or the object of a sentence.
  • A participle is a verb form that can be used as an adjective, to create verb tense, or to create a passive voice. There are two types of participles: present participle (ending -ing) and past participle (usually ending -ed, -d, -t, -en, or -n).
  • An infinitive is formed from a verb but doesn't act as a verb. It acts as a noun, adjective, or adverb, and it is actually made up of two words: to + verb.
  • Since 'cooking' is acting as a subject here, it is acting as 'gerund'.
• Hence, the correct answer is option 2.