Nine students took the SAT. Their scores are listed below. Later on$,$ they read a book on test preparation and retook the SAT. Their new scores are listed below. Construct a $95\%$ confidence interval for ${}_d.$ Assume that the distribution is normally distributed.

$\backslash$table$[[$Student$,1,2,3,4,5,6,7,8,9],[$Scores before reading book,$720,860,850,880,860,710,850,1200,950],[$Scores after reading book,$740,860,840,920,890,720,840,1240,970]]$

A$.(1\mathrm{.}651,30\mathrm{.}590)$

B$.(-20\mathrm{.}341,4\mathrm{.}852)$

C$.(-10\mathrm{.}321,15\mathrm{.}436)$

D$.(-30\mathrm{.}503,-0\mathrm{.}617)$