Final answer:
A movement along the supply curve might be caused by a change in technology, product quality, or an increase in need. Option a
Step-by-step explanation:
An improvement in technology that reduces the cost of production will cause an increase in supply. Alternatively, you can think of this as a reduction in price necessary for firms to supply any quantity. Either way, this can be shown as a rightward (or downward) shift in the supply curve.
An improvement in product quality is treated as an increase in tastes or preferences, meaning consumers demand more paint at any price level, so demand increases or shifts to the right. If this seems counterintuitive, note that demand in the future for the longer-lasting paint will fall, since consumers are essentially shifting demand from the future to the present.
An increase in need causes an increase in demand or a rightward shift in the demand curve. Option a