题目选项分析

Economist: The price of tap water in our region should be raised drastically. Supplies in local freshwater reservoirs have been declining for years because water is being used faster than it can be replenished. Since the price of tap water has been low, few users have bothered to adopt even easy conservation measures.

The two sections in boldface play which of the following roles in the economist's argument?

【选项】The first is an observation for which the second provides an explanation; the second is the main conclusion but not the only conclusion.