Final answer:
The primary purpose of conducting a census every ten years in the United States is to determine how to draw congressional district lines for representation in the House of Representatives.
Step-by-step explanation:
The primary purpose of conducting a census every ten years in the United States is to determine how to draw congressional district lines for representation in the House of Representatives (C).
By counting the number of people living in the United States and examining where they live, the boundaries of the congressional districts are adjusted to ensure fair representation among the states. This task is usually left up to the individual state legislatures after each state is informed of how many representatives they will have.
For example, more populous states are allotted more representatives in the House of Representatives, while less populous states have fewer representatives.