Read this excerpt from The Great Fire. While this was happening near the fire, more errors were taking place a mile and a half away. Chicago had recently renovated its fire alarm system, making it one of the best in the nation. Each firehouse had a watchman who scanned the immediate neighborhood for flames or smoke during the night. Overlooking the entire city was a watchman in the cupola of the Courthouse, one hundred feet above the ground. If a fire was spotted, an alarm was telegraphed (either from the firehouse or from one of the many alarm boxes situated around town) to the Courthouse; the Courthouse watchman then relayed the location of the blaze to the firehouses nearest to it. For added security, the giant Courthouse bell was also rung. Because of the drought, special Insurance Patrols had been organized and Benjamin Bullwinkle was appointed to head them. These patrols roamed the streets at night, ready to put out small fires with chemical extinguishers and turn in alarms for bigger blazes. While this system sounds very cumbersome to us, back in 1871 it was considered quite speedy and efficient.

Which quotation best reflects the main idea of this paragraph?

“While this was happening near the fire, more errors were taking place a mile and a half away.”
“Chicago had recently renovated its fire alarm system, making it one of the best in the nation.”
“Because of the drought, special Insurance Patrols had been organized and Benjamin Bullwinkle was appointed to head them.”
“These patrols roamed the streets at night, ready to put out small fires with chemical extinguishers and turn in alarms for bigger blazes.”