Chemotaxis is defined as a response to a chemical gradient of attractant or repellent molecules in the bacterium's environment. if the environment contained a gradient of attractants, which bacterium would be most likely to have a net movement toward the signal? (choose the motility deep test result as your indicators.) select one: a. the motility deep has a single green line that corresponds to where you had stabbed the needle. b. the motility deep is colorless. c. the motility deep is entirely red. d. the motility deep has a single red line that corresponds to where you had stabbed the needle.