The following are the expressions about giving dimensions for mechanical drawing. Which one among them is correct?
A.
When the diameter of a spheres is dimensioned, the dimension line should go through the center of the sphere, and add a“φ” before the dimension figure.
B.
When a whole circle or an arc over 180°is dimensioned, a "Ø" should be added before the dimension figure.
C.
When a whole circle or an arc of 180°is dimensioned, a "Ø" should be added before the dimension figure.
D.
When a corner is dimensioned, the size of it should be indicated with diameter, and a symbol“φ”should be given before the dimension figure.