Read the excerpt from "the great san francisco fire."

the first fire to break out after the quake was at a chinese laundry across the street from a firehouse. however, there was no water to fight it since the water mains had been ruptured by the quake. the main reservoirs of water for the city were 20 miles away, and some of the pipelines to them had been destroyed because they were constructed along the quake’s fault line. the blaze soon roared like a seething, famished beast lapping up its spoils. then two massive fires flared up within two blocks of each other in the western addition section of the city. another one broke out in the mission district. in the downtown area dozens of fires erupted. firefighters were able to quell the flames in the western addition with the use of three fire engines. the fire in the mission district was subdued with water found blocks away in a hydrant. then the firefighters began to head downtown to try and extinguish the fiery deluge there. most of the large fires downtown became one. at one point it became a three-mile-wide wall of raging flames with billowing black clouds of smoke. in one area, a cistern that held 100,000 gallons of water was drained completely without making a dent in the spewing blaze. fireboats sprayed water in a desperate attempt to quash the fuming flames along the waterfront.

which sentence from the paragraph uses a cause-and-effect structure?

a. "the first fire to break out after the quake was at a chinese laundry across the street from a firehouse."
b. "the fire in the mission district was subdued with water found blocks away in a hydrant."
c. "then two massive fires flared up within two blocks of each other in the western addition section of the city."
d. "however, there was no water to fight it since the water mains had been ruptured by the quake."