Assuming concrete below the neutral axis to be cracked, the shear stress across the depth of a singly-reinforced rectangular beam section

• A. increases parabolically to the neutral axis and then drops suddenly to zero value
• B. increases parabolically to the neutral axis and then remains constant over the remaining depth
• C. increases linearly to the neutral axis and then remains constant up to the tensioned steel
• D. increases parabolically to the neutral axis and then remains constant up to the tensioned steel