They are most mainly consists of "Keratin"
So, option B is your answer.
Hope this helps!
<span>The answer is letter B. <span>
<span>Motor
neurons tend to function less as age sets-in in a particular individual.
Reaction time is the ability to respond quickly to stimulus presented in a
given situation. An example of this is the gun start that is commonly used in
athletic competitions where a person reacts quickly to the signal and performs
the activity. As we age, our
sensory systems deteriorate and as a result some of the skills we have when we were
younger are not as effective as it was when we turned into mature adults. </span></span></span>
