This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to create a solar panel water heater
Get a double-glazed unit for the sunlight to pass through.
Glaziers and window manufacturers sometimes have scrap units for patio doors or large windows that can be bought very cheaply. Glass with a low-emissivity coating such as pilkington k glass is ideal.

Select from: A). Get a single-panel room radiator that is slightly smaller than the glass unit. Scrap yards sometimes have old radiators, or ask a plumber who is refurbishing a central heating system.. B). Cut out two panels for the light fixtures in your home. They should be at least 24 inches (61 cm) by 36 inches (61 cm).. C). Decide what sizes you want your solar panels to be. Some of them will be big enough that able-bodied people are able to fit into them.. D). Find a plug-in faucet. A tap with a hard rod is best, as power is concentrated in the chamber..
The answer is:
A).