the undercover agent still investigating the case is a run-on sentence
Yikes: Interjection. A word to express emotion. In this case kind of frightened.
Huge: Adjective specifies the quality size or amount of nouns or pronouns. In this case very big.
Test. Common noun. These are generic names of things, animals, persons or places.
On Friday. Preposition, specifies location (place) or location in time.
Barely. Adverb, also used to describe adjectives verbs or another adverb. In this case barely is describing the verb study.
Studied. Simple Past tense of verb Study.
In that case the answer should be number 3.
