The breadth of a ribbed slab containing two bars must be between______________?
A. 6 cm to 7.5 cm
B. 8 cm to 10 cm
C. 10 cm to 12 cm
D. 12 cm to 15 cm
A. 6 cm to 7.5 cm
B. 8 cm to 10 cm
C. 10 cm to 12 cm
D. 12 cm to 15 cm