GMAT Critical Reasoning (CR) | Re: OG 2016 - Demand for electricity

In this question, I mistook the conclusion to be "I propose passing ordinances requiring energy-conservation measures in all city departments." because "We must therefore begin to curtail usage". I didn't take "We must therefore begin to curtail usage" as the conclusion, hence I was confused between B and D. How does one fin conclusion in such passages?
Regards,
Abhijit

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