[单选题]
The efficiency of a Carnos1(lv:z ;gv2 -tk0uf 6wbwool*jy/ ky6wz*do t engine is 35.0%. What is the temperature of the cold reservoir if the temperature of t*zydyk woj /6*he hot reservoir is $500 ^{\circ}K$?
A. $175 \; K$
B. $325 \; K$
C. $269 \; K$
D. $231 \; K$
