If Sb, is the average bond stress on a bar of diameter subjected to maximum stress , the length of the embedment is given by_____________?

If Sb, is the average bond stress on a bar of diameter subjected to maximum stress , the length of the embedment is given by_____________?

A. l = dt/Sb
B. l = dt/2Sb
C. l = dt/3Sb
D. l = dt/4Sb