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 

Pro insulin undergoes extensive posttranslational modification along the production pathway .

light dependent reactions:

release oxygen during the photolysis of wateroccur in the granaproduce atp

light independent reactions:

fix carbon dioxide occur in the stromaproduce glucose

hope this !