In the following passage, some of the words have been left out. Read the passage carefully and select the correct answer for the given blank out of the four alternatives.
Passage:

The climate question _____________ a leapfrog era for India’s development paradigm. Already, the country has chalked out an _____________ policy on renewable energy, hoping to generate a massive 175 gigawatts of power ____________ green sources by 2022. This has to be _____________ pursued, breaking down the barriers to wider ___________ of rooftop solar energy at every level and implementing net metering systems for all categories of consumers.