What are the thermal boundary conditions for polypropylene (PPP) or polyvinyl chloride (PVC) cylinder in Lab 6?a. Constant temperature at the inner surface, b. constant temperature at the outer surfaceConstant temperature at the inner surface, c. zero temperature gradient at the outer surfaceUniform heat flux at the inner surface, d. constant temperature at the outer surfaceUniform heat flux at the inner surface, e. zero temperature gradient at the outer surface