This photograph shows a protion of the Monahans Sandhills in northwest Texas. Monahans Sandhills are noted for their sand dunes that can be up to 21 m (70 feet) high. The Monahans Sandhills are part of a semi-arid ecosystem that received 310 mm (21 inches) of rain on average per year. Another picture of the same area taken weeks before shows that the shape and location of some sand dunes have changed. Which of these most likely caused the changes in the dunes?

A. mechanical weathering of rocks

B. wind erosion of sand particles

C. water deposition of pebbles

D. chemical weathering of the rocks