An interjection can be
a hand gesture
an exclaimed sound
a basic sound combination
a word that stands alone

an exclaimed sound

a basic sound combination

a word that stands alone

Explanation:

Let's find out what interjection is.

An interjection is a part of speech that shows the emotion or feeling of the speaker/author. They are also named as exclamations. Mostly interjections are used in fiction or artistic writing and usually are followed by an exclamation point (which is also used to show emotion).

Interjections can be:

Adjectives that are used as interjections - Nice! You won this game so fast.

Nouns or noun phrases that are used as interjections - Holy cow! I forgot my purse!

Short clauses that are used as interjections - Mr. Smith is our English teacher. Oh, the horror!

Some interjections are sounds - Ugh! I’m never doing that again!

Or some sound combination - Uh-oh! I guess I am in serious trouble.

Some words are primarily interjections: Eureka!, oops! yahoo! etc.

So the correct answer is that interjection can be an exclaimed sound, sound combination, and a word that stands alone.

I hope it helped you :)