Answer:
The correct answer is 11 years
Explanation:
Summer Olympics every 4 years
US Senator runs for reelection every 6 years
Both events occurred last year
Next Summers Olympics in 3 years, 7 years, 11 years, 15 years, 19 years, 23 years.
Next US Senator reelection in 5 years, 11 years, 17 years, 23 years.
The next time US Summer Olympics and the US Senate will take place the same year, will be exactly in 11 years.