A Cylindrical Tank Is Assembled by Welding Steel Sections Circumfer- $38 \mathrm{MPa}$

A cylindrical tank is assembled by welding steel sections circumfer- entially. Tank diameter is 1.5 m, thickness is 20 mm, and internal pressure
Is 2.0 MPa. The maximum stress in the heads of the tank is approximately: (A) $38 \mathrm{MPa}$
(B) $45 \mathrm{MPa}$
(C) $50 \mathrm{MPa}$
(D) $59 \mathrm{MPa}$