Which protist produces its own food but is apparently unable to move on its own?

Identify whether each of the following statements best illustrates the concept of consumer surplus, producer surplus, or neither. statement consumer surplus producer surplus neither a local store was having a sale on textbooks, so i bought a used textbook for my brother. i sold a watch for $61, even though i was willing to go as low as $55 in order to sell it. even though i was willing to pay up to $116 for a used laptop, i bought a used laptop for only $110.