The answer is A. Dew point is the temperature at which air will turn into water vapor, a state between gas and liquid. If the temperature is further cooled down to lower than the dew point, water will condense, in other words, the gas state of air will turn into liquid state of water.
The variable that researchers manipulate is the independent variable.
The reason for this is because in experiments different manipulations are often introduced. The sole purpose of these manipulations is to see whether they will affect our independent variable and if they will change its value.
Hydrogen, oxygen, and nitrogen atoms.
