Trevor examines some water from the open ocean and finds that it contains several single-celled and multi-celled organisms. What term should Trevor use to describe the organisms based on their method of locomotion?

Classification of the organisms based on their method of locomotion would be flagella, pili or gliding. The structure that offers the highest motility of those 3 would be flagella.

An organism with flagella could be further classified on the number of flagella such as: atrichous (no flagella), mono trichous (1 flagella), amphitrichous (flagella on both side), lophotrichous (many flagella on one end), peritrichous (flagella all around the membrane)