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

A cylindrical tank is assembled by welding steel sections circumferentially. Tank diameter is 1.5 m, thick- ness 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) $59 \mathrm { MPa }$