I studied it in 3rd standard so I don't remember much. As much as I can remember CPU means Computer Programming Unit. Computer doesn't have a full form it is a simple word that means something that computes or calculates.
Answer:
<em>Reflex </em>
Explanation:
A reflex or reflex action <em>works in response to a stimulus in an involuntary and almost immediate movement.</em>
Neural connections called reflex arcs make a reflex possible, that can act on an impulse before it reaches the brain.
The reflex is then an automatic response to a stimulus not receiving or needing active thinking.
Population census is data collected by the government which gives them an idea of the total population in a country/suburb or city. This information can also be sorted to see how many females/males, children/adults and visitors/residents