What essential characteristic(s) does a good experiment have? A. A control group is given the experimental treatment.

B. A single variable is tested.

C. A control is used.

D. Both b and c

Answerland;

Your answer is d. silli hope this ! : ) i left an explanation down below if you need it: a sill forms when hot magma squeezes between layers of rock to form a hardened sheet of rock. a sill is basically a tabular sheet intrusion between old layers of sedimentary rock, volcanic beds, or in the direction of foliation inherent in metamorphic rock. the word sill means a concordant intrusive sheet.