They did it because they feared that without a specifically enumerated bill of rights that the government could become tyrannical in the same manner in which the British were tyrannical. They believed that rights of people and states should be written and stated officially instead of just being implied since implied things are easy to exploit and maneuver according to your needs.
The location of the famous stand by 300 Spartans against the Persian army is called.....Thermopylae....
Epic movie.. :D
Thus, your answer.
C. Persia was a tiny country compared to the size of it empire