A Cylindrical Tank Is Assembled by Welding Steel Sections Circumferentially $2.0 \mathrm { MPa }$

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 shear stress in the heads is approximately: $2.0 \mathrm { MPa }$

A) $19 \mathrm { MPa }$
B) $23 \mathrm { MPa }$
C) $33 \mathrm { MPa }$
D) $35 \mathrm { MPa }$