[单选题]
The efficiency of a Ca /nva:pr3d1(m7rk:sz j wdo /yrnot engine is 35.0%. What is the temperatu 4/wlj0 +sved6yhni7 zre of the cold reser6iv7zhd wn/y0ejls4 +voir if the temperature of the hot reservoir is $500 ^{\circ}K$?
A. $175 \; K$
B. $325 \; K$
C. $269 \; K$
D. $231 \; K$
