A thin spherical shell of internal diameter d is subjected to an internal pressure p. If $${\sigma _{\text{t}}}$$ is the tensile stress for the shell material, then thickness of shell is equal to

A. $$\frac{{{\text{pd}}}}{{{\sigma _{\text{t}}}}}$$

B. $$\frac{{{\text{pd}}}}{{2{\sigma _{\text{t}}}}}$$

C. $$\frac{{{\text{pd}}}}{{3{\sigma _{\text{t}}}}}$$

D. $$\frac{{{\text{pd}}}}{{4{\sigma _{\text{t}}}}}$$

Answer: Option D