Me los mangos

options:
gustan
gusta
gusto
gustamos

Gustan

Explanation:

There are 2 forms of the verb gustar: gusta and gustan

We can automatically eliminate gusto and gustamos, because they are not good choices.

Gusta is used for singular items or verbs.

⇒Me gusta el cuaderno (I like the notebook)

⇒Me gustaa pescar (I like to fish)

Gustan is used for plural items.

⇒Me gustan los gatos. (I like cats)

Me los mangos

"Los mangos" is plural, because the article is "los", and there is an "s" on the end of the word.

Therefore, we need to use gustan.

Me gustan los mangos (I like mangoes)