Answer:
Dependent variable: Blue or pink color of flowers.
Independent variable: The treatment given to hydrangea plants to change color.
Constant variables: The composition of the soil where hydrangeas are planted, and the atmospheric condition.
Step-by-step explanation:
The independent variable is the variable that changes or is controlled for the study of its effects on the dependent variable, in this case, the independent variable is the treatment that hydrangea plants do to change color. The dependent variable is the variable that is measured, in this case, it will be the type of color, either blue or pink of the flowers. A constant variable is one that cannot be changed, in this case they would be the composition of the soil where hydrangeas are planted, and the atmospheric condition.