Cosmo is a scientist. He is conducting an experiment to determine if microscopic yeast particles are living organisms. He divides a Petri dish into four sections and spreads a sample of yeast into each section. His Petri dish is pictured below.

Cosmo knows that yeast reacts chemically with sugar. So he adds different amounts of sugar to each section of his Petri dish. He is careful to keep each section separated from the others. In one of the sections, Cosmo does not add any sugar at all.

He waits one week and then carefully observes each sample of yeast under a microscope. He makes several observations. These observations are listed below.
Each sample of yeast remained separate from the other three samples.

The three samples that were given sugar showed evidence of a chemical reaction.

The sample that was given the greatest amount of sugar reacted with the sugar the most.

The yeast that received no sugar responded by forming and releasing spores.
Which observation provides the best evidence that Cosmo's yeast particles are living organisms?
A.
Observation #4
B.
Observation #1
C.
Observation #3
D.
Observation #2