<span>In a 2-dimensional coordinate system, the x- and y-axes
are typically perpendicular to each other. (C) </span>
It's not true.
The crucial principle for a scientific experiment is to keep only ONE variable at a time.
In this case, the variable of this experiment is actually the tomato is in sunny part or in shady part, instead of whether applying Ca fertilizer.
It often requires STANDARD reaction time