Answer:
A and B
Explanation:
The two statements on the options which best describe jet streams are the options A and B. Option A describe the movement pattern of jetstreams as this narrow and of strong wind which occurs at very high levels above the atmosphere have been established to move in the west to east direction. Also the boundary in which jetstreams flow is the boundary between the two distinct air masses, the cold and warm air mass. Hence, statement B is also a correct description, that they seperates air masses of different temperature.
