What must be true when two substances form a mixture? A. they are the same size
B. they are two of the same type of substance
C. they are both metals
D. they do not react chemically

What is the function of the somatic nervous system? connects the brain and the spinal cord to the rest of the body carry signals to the muscles and glands includes all nerves controlling the muscular system and external sensory receptors controls internal organs like the heart and bladder