Charlie hypothesizes that if he adds earthworms to a compost pile, it will decompose twice as fast as a compost pile without earthworms. which of the following steps could compromise his experiment?
start two compost piles at the same time with the same materials.
add earthworms to one compost pile.
add decomposing bacteria to the other compost pile.
rate the level of decomposition in each compost pile every week.
report his results.
a.
step 1
b.
step 4
c.
step 2
d.
step 3