What Is a "Qanat

What is a "qanat"?

A) an irrigation system, developed in Iran, that taps into groundwater through a series of gently sloping tunnels
B) a type of subsistence agriculture practiced on oases
C) a formal title given to the monarch (national leader, like a king or queen) in the country of Saudi Arabia
D) the practice of seasonally moving livestock to cooler, greener, high country pastures in the summer, then returning them to valley and lowlands for fall and winter grazing
E) water supplies stored underground during earlier and wetter climatic periods