The correct answer is: Reapportionment is based on population changes recorded by the U.S Census. Reapportionment is the act of being reapportioned. The government of The United States uses the Census as a tool to calculate the amount of people living in the country. Once they collect the information, they use the results to many different ends. One of them is the redistribution of representation in the Congress or other legislative bodies. If the population of certain city or State had increased, that increase has to be represented in the Legislative Power.