For numbers 7,8 and 9, please refer to the situation below.

Jaydee and Jayson wanted to find out if varying amount of chicken manure as fertilizer can affect the growth of algae in a fishpond.
7.What should be the manipulated (independent) variable?
A.growth of algae.
B.time of observation
C.Size of the pond
D.amount of chicken manure
8.Which will be the responding (dependent) variable?
A.growth of algae
B.time of observation
C.size of the pond
D.amount of chicken manure
9.Which 2 are the controls?
A.growth of algae
B.time of observation
C.size of the pond
D.amount of chicken manure​