  The preceding Comment by Xu et al. (Phys. Rev. Lett. 122, 059803 (2019);
arXiv:1808.05390) erroneously applies the entropic stress expression in our
Letter (T.C. O'Connor et al., Phys. Rev. Lett. 121, 047801 (2018);
arXiv:1806.09509) to transient stress. In addition, the authors only apply this
expression at extreme extension rates where we clearly showed deviations from
the entropic stress expression for steady-state extensional flow. Hence the
surprisingly minor discrepancies noted in the Comment between observed and
"predicted" stress are entirely expected and have no bearing on the discussion
or conclusions in our Letter.
