A cured phenolic resin sample was analyzed with DMA $($see results below$).$ Use these results to calculate the molecular weight between crosslinks $(M_c)$ using rubber elasticity correlations for epoxy$-$phenolic thermosets. Assume that the bulk density of the resin is approximately $1\mathrm{.}15\frac{g}{c}{m}^3$ at all temperatures.

A$.30\frac{g}{m}ol$

B$.170\frac{g}{m}ol$

C$.330\frac{g}{m}ol$

D$.700\frac{g}{m}ol$

E$.2100\frac{g}{m}ol$