Concept:A population census is a complete count of all people in a country at a given time.
It supplies data needed for economic planning and measurement.
Explanation:An accurate census provides reliable information about the total population.
This total is used to calculate a country's per capita income.
Per capita income is found with the formula:
Per capita income=Total populationNational incomeWithout an accurate census, the population figure would be wrong.
That would make the per capita income estimate inaccurate or misleading.
So, the most direct importance of an accurate census here is to help measure per capita income.
Answer:C. estimate a country's per capita income.