The following sets of statements contain common errors. Identify and explain each error:
a. Supply decreases, causing prices to rise. Higher prices cause supply to increase. Therefore, prices fall back to their original levels.

b. The supply of pineapples in Hawaii increases, causing pineapple prices to fall. Lower prices mean that the demand for pineapples in Hawaiian households will increase, which will reduce the supply of pineapples and increase their price.