<span>The correct answer is d. increase the rate of breathing.</span>
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Peripheral chemoreceptors (the carotid and aortic bodies) can sense hypercapnia (high CO2) and then they send a signal to the breathing centre. Breathing centre is in medulla oblongata which regulates breathing movements. When CO2 reaches a certain level, a signal is sent to trigger an inhalation and the rate of breathing is increased.</span>
B is your answer and explanation because I know ;)
F=ma
m=40 kg
a= unknown
f= 400 N
rearrange equation to f/m=a
so (400)/(40) = 10 m/s/s