In the control group, how did the number of grass blades change over the three week period?
In the experimental group, how did the number of grass
blades change over the three week period?

Was there a measureable difference in the number of
grass blades between the control group and the
experimental group at the end of three weeks?

answer is: naturally occurring solid, inorganic compound or element is mineral.

minerals usually have crystalline form, that means than crystal constituents (atoms, molecules or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions.

for example magnetite is a mineral of iron oxide (fe₂o₃).

calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (caco₃).

dolomite is an   carbonate mineral composed of calcium magnesium carbonate (camg(co₃)₂).

elements make up everything, and they combine to make compounds.

the answer is c