CLO 2: A 7-m span simply supported beam carries a uniformly distributed ultimate load of 150 kN/m. The dimensions of the beam section are b = 300 mm, d - 600 mm. The beam is reinforced with bars of 25-mm diameter in one row, f'c-21 MPa, and Fy = 420 MPa. Use # 10 U-shaped stirrups. Neglect the column width. The stirrup spacings (s) is equal to a 210 mm b. 120 mm . 140 mm d. 80 mm