Final answer:
The percentage of seats in the US House of Representatives up for election every two years is a.100%.
Step-by-step explanation:
The percentage of seats in the US House of Representatives that is up for election every two years is a. 100%.
According to the US Constitution, all 435 members of the House of Representatives are elected every midterm and presidential election year. Each representative serves a two-year term, and the number of representatives a state has is based on its population.
For example, larger states such as California and Texas have more representatives, while smaller states like Wyoming and Vermont have fewer representatives. Overall, the House of Representatives provides proportional representation based on population.