Investigators designed a "physical activity intervention" to increase physical activity at school and at home. They also designed a "nutrition intervention" that improved school lunches and offered ideas for healthy home-packed lunches. Each participating school was randomly assigned to one of the interventions, both interventions, or no intervention. The researchers observed physical activity and lunchtime consumption of fat.

1.) The response is

A) the two intervention techniques.
B) the physical activity and lunchtime consumption of fats.
C) the "nutritional intervention."
D) the "physical activity intervention."

2.) This study uses the principles of

A) confounding.
B) matching.
C) randomization.
D) all of the above.