Can keep you alert and sharpen your concentration.
a. stress response
b. exhaustion
c. resistance
d. none of the above

Stress response - A can keep you alert and sharpen your concentration.

The reson for this is that a short-term stress response can keep your body ramped up and prepared for physical action and a short-term increase in bodily function (those related to flight and fight) is present. This is so because when you're like this, you become more focused on a potential and possible predator that could hurt you and for that reason you then decide what is the best course of action. 

One answer could be erosion