In a doubly-reinforced beam, if c and t are stresses in concrete and tension reinforcement, d is the effective depth and n is the depth of critical neutral axis n, the following relationship holds good

• A. mc/t = n/(d - n)
• B. (m + c)/t = n/(d + n)
• C. (t + c)/m = (d + n)/n
• D. mc/t = (d - n)/t