Why does cacl2 need to be added to cells to make them 'competent'? why does cacl2 need to be added to cells to make them 'competent'?

Imagine a person stepping on a pin and pulling his or her foot away. look at the reflex arc of this scenario below. which statement best describes the image? a)the sensory nerve carries the signal from the effector to the interneuron, and the motor neuron carries the signal to the receptor. b)the motor nerve carries the signal from the receptor to the interneuron, and the sensory neuron carries the signal to the effector. c)the sensory nerve carries the signal from the receptor to the interneuron, and the motor neuron carries the signal to the effector. d)the sensory nerve carries the signal from the receptor to the motor neuron, and the interneuron carries the signal to the effector.