Brass Pipe Is Twisted by Torques T =800 N $3.5 ^ { \circ } \text {, }$

brass pipe is twisted by torques T =800 N. m acting at the ends causing an angle of twist of $3.5 ^ { \circ } \text {, }$ . The pipe has the following properties: $L = 2.1 \mathrm {~m} , d _ { 1 } = 38 \mathrm {~mm} , \text { and } d _ { 2 } = 56 \mathrm {~mm}$ . The shear modulus of elasticity G Of the pipe is approximately:

A) $36.1 \mathrm { GPa }$
B) $37.3 \mathrm { GPa }$
C) $38.7 \mathrm { GPa }$
D) $40.6 \mathrm { GPa }$