All organisms fit into one of the two following categories.
select one:

a. consumers and decomposers
b. scavengers and detritivores
c. producers and consumers
d. none of these

Abird flies by moving its wings up and down. which two systems are most directly responsible for the movement of a bird's wings? a. skeletal and muscular systems b. respiratory and muscular systems c. skeletal and digestive systems d. respiratory and digestive systems