species can be valued for their ecosystem services or intrinsic value. which of the following statements values species for their intrinsic value? a.) chickens should not have to live their lives trapped in a cage. b.) paula volunteered to help plant trees in her city to help regulate air quality. c.) alberto uses alpaca wool to knit sweaters because customers demand its quality. d.) an elementary school class takes a field trip to a pond to study its frog population.