A factor that is kept the same between the control and experimental groups is called?

In a controlled experiment, the control group and the experimental groups are the same except for a factor in the experimental groups called a. variable parameter. In a controlled experiment, the factors that are kept the same between groups are called. controlled parameters.

Aneutral atom must have the same number of neutrons and protons? no, they must have the same number of protons and electrons

Ibelieve is d but i’m not 100% sure