SIGMA _1=\frac{PD}{2t}\)Longitudinal stress is, \(\sigma _2=\frac{Pd}{4t}\)Radial stress is, \(\sigma _3=0\)And the Absolute maximum shear stress is, \(\tau _m=\frac{\sigma _1-\sigma _3}{2}=\frac{Pd}{4t}\)Calculation:Given:d = 0.5 × 2 = 1 m = 1000 mm, P = 2 MPA, t = 0.52 - 0.5 = 0.02 m = 20 mm THEREFORE, \({\tau _{max}} = \frac{{2 ~\times~ 1000}}{{4~×~ 20}} = 25\;MPa\)As, in option 25 MPa is not available so we NEED to choose more stress than 25 MPa.