What begins when a neuron is stimulated by another neuron or by a stimulus in the environment?
a. a threshold
b. a resting potential
c. an impulse
d. a dendrite

The question is asking to choose among the following that states what could happen when a neuron is stimulated by another neuron or by a stimulus in the environment and in my research i would say that its letter C. an impulse . I hope you are satisfied with my answer and feel free to ask for more 

Both prokaryotic and eukaryotic cells have ribosomes and cell membranes

Ascientist will use that to figure out how or why things are the certain way they are i hope this