Answer:
A: The diameter is 6in.
B: The radius is 3in.
C: The diameter is given to us in the problem. A line is drawn out that strikes through the center point. of the circle, and it is labeled 6in in the middle, so we can deduce that it is the diameter. The radius of a circle is 1/2 the length of the diameter, so 6/2 = 3in. If the 6in was on either side of the line, then that would be labeling the radius.