Answer:
2. The number of times they can be re-elected.
Step-by-step explanation:
There are two houses within the U.S. Congress. The founding fathers wanted to make the two houses different enough so that all citizens would be represented equally. Senators and Representatives have other numbers of years that they serve (Senators 6 years, Representatives 2 years), several elected officials in their house (Senators 100 members, Representatives 435 members), and the groups of people they are accountable to (Senate is responsible to citizens of their home state, Representatives accountable to citizens in their Congressional districts). They also have a different minimum age at the time of their election. (Representatives must be at least 25 years old, while Senators must be at least 30 years old at the time of their election.) The length of citizenship is also different for a Senator and a Representative. (A Senator has to be a U.S. citizen for at least nine years, while a Representative only has to be a citizen for seven years.) One similar detail between the Senate and the house is that officials can be re-elected unlimited times.