The true statement is : ( C ) most protists can respire with and without oxygen at will
Protists are eukaryotic organisms that can respire either through aerobic respiration ( the use of oxygen ) mostly for obligate protists. while certain parasitic protist can respire through anaerobic respiration process ( without the use of oxygen ).
Protists can be Fungi, animal or even plants therefore from the options given above most protists can respire with and without oxygen.
Hence the true statement is most protists can respire with and without oxygen at will.
Learn more about protist : https://brainly.com/question/17546239