Final answer:
The best expression for the circumference of a circle when the diameter is 19 inches is C = π × 19 inches.
Step-by-step explanation:
The question concerns the relationship between the circumference of a circle and its diameter.
The circumference (C) of a circle can be calculated using the formula C = πD, where D is the diameter of the circle and π is a mathematical constant approximately equal to 3.14159.
Given that the diameter of the circle is 19 inches, we can substitute this value into the formula to find the circumference.
So, the expression which best represents the value of C, the circumference, when the diameter (D) is 19 inches is:
C = π × 19 inches.