Verbally explain the difference between a change in "quantity supplied" and a change in supply. Considering the supply side of the market for lawn-mowing services, what kind of change (increase or decrease, in quantity supplied or supply) would each of the following events cause?

a. There is a rise in the price of gasoline used to run power mowers.

b. There is a rise in the going price for lawn-mowing services.

c. More people decide to offer to mow lawns.

d. A new lawn mower is invented that is cheap and makes it possible to mow lawns at a lower cost.