A movement along the demand curve is typically caused by changes in the price of a good. Therefore, option (3) "Fall in price of a good" is the correct answer.

The other options represent factors that can shift the entire demand curve rather than causing a movement along it:

(1) A rise in income of consumers can shift the demand curve, especially for normal and inferior goods.

(2) An expected rise in future prices may lead to increased current demand, shifting the demand curve to the right.

(4) A fall in the price of a substitute good can shift the demand curve for the original good, as consumers may switch their preference from the more expensive substitute to the now cheaper original good.