Deserts advance linearly, in easily mappable patterns.
true
false

False. Deserts do not expand linearly or in mappable patterns due to the changing nature of weather patterns. Deserts are formed through the process of erosion which breaks down into sand particles over time, through wind action for example, as the wind carries sand particles, this shifts the shape and form of sand dunes and deserts over time. 

The answer is c) people evacuated but almost all returned

Answer primary waves;