Photo quiz: Gear for green buildings

The answer to the previous question is A. Those tubes are cutting-edge solar hot water technology. The tubes circulate a combination of water and alcohol, which turns to steam in the sun. The heat generated by the tubes is eventually transferred to a hot water tank to preheat a traditional hot water heater.

Next question: This building has two types of solar energy technologies on it. Pick the correct combination:

A. Two solar hot water panels on left and three solar photovoltaic panels on right.

B. Five solar photovoltaic panels.

Answer and new question on next page.

Photo by Martin LaMonica/CNET

Caption by Martin LaMonica