Amodel organism is a species that researchers study to better understand certain biological processes. mollusks and arthropods are commonly used as model organisms for studying mechanisms of learning and memory, while sponges and jellyfish are not. why is this? a. mollusks and arthropods exhibit cephalization, while jellyfish and sponges do not. b. mollusks and arthropods exhibit segmentation, while jellyfish and sponges do not. c. mollusks and arthropods can detect stimuli from their environment, while jellyfish and sponges cannot. d. mollusks and arthropods can respond to changes in their environment, while jellyfish and sponges cannot.