I believe substance A is the depressant, substance B is the water and substance C is the stimulant.
The data to support this is the data that was shared by the 9 groups in Mrs. Moreno's second period class.
The method I used to come to this conclusion was by averaging each groups data on each different substance (A, B, C).
By averaging the data I was able to find out that the average heartbeat of the worms in each substance.
Substance A: 26.99 (Depressant)
Substance B: 31.26 (Water)
Substance C: 33.81 (Stimulant) .