Which of the following statements about campaign spending in Senate elections is true?
- Incumbents generally spend less money than challengers in Senate campaigns.
- Incumbents and challengers generally spend the same amount of money in Senate campaigns.
- Incumbents generally spend more money than challengers in Senate campaigns.
- Incumbents and challengers in Senate campaigns are legally limited to spending only $2 million.
- Incumbents and challengers in Senate campaigns are legally limited to spending only $5 million.