A recent review of pay scales indicates that CEO's now earn an average of 419 times more pay than blue-collar workers, compared to a ratio of 42 times in 1980. (A) that CEO's now earn an average of 419 times more pay than blue-collar workers, compared to a ratio of 42 times(B) that, on average, CEO's now earn 419 times the pay of blue-collar workers, a ratio that compares to 42 times(C) that, on average, CEO's now earn 419 times the pay of blue-collar workers, as compared to 42 times their pay, the ratio(D) CEO's who now earn on average 419 times more pay than blue-collar workers, as compared to 42 times their pay, the ratio(E) CEO's now earning an average of 419 times the pay of blue-collar workers, compared to the ratio of 42 times
答案是c,不过对于C中的their有疑问：their指代谁？在语法中their的指代原则是什么？
期待一个满意的答复~
