In a 2019 study, Jeremy Gunawardena and colleagues found that the single-celled protozoan Stentor roeseli not only uses strategies to escape irritating stimuli but also switches strategies when one fails. This evidence of protozoans sophisticatedy "changing their minds" demonstrates that single-celled organisms may not be limited to _______ behaviors.

Which choice completes the text with the most logical and precise word or phrase?