maximum shear stress in wall

Question

A gas stored in a cylindrical tank of inner radius 7 m and wall thickness 50 mm. The gauge
pressure of the gas is 2 MPa. The maximum shear stress (in MPa) in  the wall is

(a) 35         (b) 70         (c) 140        (d) 280

Answer 1

Given a gas stored in a cylindrical tank of specified inner radius and wall thickness
and gauge presure is known