Which combination of terms correctly refers to exotic species?

I introduced species

II. alien species

III. non-indigenous species

IV. non-native species

Choose the correct combination.

I, II, III and IV

The correct answer is Option (4)-I, II, III and IV 

Exotic species are also called introduced species, alien species, non-indigenous species, and non-native species.

• Introduced species are species that have been intentionally or unintentionally brought into an area outside of their natural range.
• Alien species are species that are not native to a particular area.
• Non-indigenous species are species that are not native to a particular area and have been introduced by humans.
• Non-native species are species that are not native to a particular area and have been introduced by humans.

Therefore, all of the options are correct.