Middle-latitude cyclones are fueled by
a. energy from falling precipitation.
b. polar continental air masses.
c. air high up in the atmosphere.
d. the movement of stationary fronts.

C. air high up in the atmosphere.

Cyclones outside the tropics are called as mid-latitude cyclones. In a typical cyclone wind moves in a circular fashion. As the surface wind rises it begins to rotate. The center of the cyclone origin site remains at low pressure. It results in less denser air to move upwards in the higher atmospheric layers. The movement of this air current is directionless. Therefore, middle-latitude cyclones are fueled by air currents air high up in the atmosphere.

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i think it would be b. tissue because an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.