Question

select all of the proper nouns.
in the nile river, crocodiles bask in the sunlight to keep warm.

Explanation:

Proper nouns are specific names of people, places, organizations, etc. In the sentence "In the Nile River, crocodiles bask in the sunlight to keep warm", "Nile River" is a specific geographical place (a river), so it is a proper noun.

Answer:

Nile River