‘Net metering’ is sometimes seen in the news in the context of promoting the

Net metering is a billing mechanism designed to incentivize the production and use of solar energy by households/consumers.

It works by crediting owners of solar energy systems for the excess electricity they supply to the grid. If a household generates more electricity than it consumes (typically through rooftop solar panels), the surplus is fed back into the grid, and the homeowner receives credit for it.

Hence, option a is the correct answer.

Source:

• [mass.gov - Net Metering FAQs](http://www.mass.gov/eea/grants-and-tech-assistance/guidance-technical- assistance/agencies-and-divisions/dpu/net-metering-faqs.html)