A nylon spacer $)=(82\mathrm{.}2\frac{m}{mC}$ long is heated from $20C$ to $40C.$ If it's constrained, what's the strain?

A$.82\mathrm{.}2{10}^{-6}$

B$.2\mathrm{.}89{10}^{-3}$

C$.4\mathrm{.}11$

D$.1\mathrm{.}64{10}^{-3}$