127. In theory, international civil servants at the United Nations are prohibited from continuing to draw salaries from their own governments; in practice, however, some governments merely substitute living allowances for their employees' paychecks. assigned by them to the United Nations. (A) for their employees' paychecks, assigned by them (B) for the paychecks of their employees who have been assigned(B) (C) for the paychecks of their employees, having been assigned (D) in place of their employees' paychecks, for those of them assigned (E) in place of the paychecks of their employees to have been assigned by them

我的问题是a答案还有c答案，黄色部分，是一个语法现象么？

og解释说a中修饰最近的名词paychecks，c怎么就修饰不明确了呢？

请指点，谢谢！