All protists are

A. autotrophs

B. heterotrophs

C. eukaryotes

None of the above

Explanation:

There exist some protists which are autotrophs such as green algae others are heterotrophs such as amoebas and paramecia but known of protists are eukaryotes, they are all prokaryotes. Don't forget concepts, eukaryotes have a true nucleus and other memebrane bound organelles such as mitochondria and since protists lack such structures, they cannot be considered as eukaryotes.

c. eukaryotes