Wind speeds increase higher up from the Earth's surface because

A. friction from landscape features doesn't slow them down.

B. oxygen levels are decreased, making air movement quicker.

C. the atmosphere is composed of heavier molecules at lower atmospheric levels.

D. the wind is augmented by the solar wind.

A. Friction from the landscape doesn't slow them down. as altitude increases, there wind speed increases primarily due to less friction slowing down the wind. Earth's terrain by its very nature provides friction which slows the wind down. Buildings, tress, hills, etc all slow the wind. The higher up you go, there is less things to impede the wind and provide any friction. The wind speeds are therefore higher at the high altitudes.