“they would like to see”这部分是定语从句.在复合句中,修饰名词或代词的从句叫定语从句,“they would like to see”这部分是由“that ”引导的定语从句,代替 which ,在从句中作谓语动词 see 的宾语.“they would like to see”修饰先行词 the plan .这句话的意思是:经理们已经讨论了想要在明年实施的计划.
PS：辨认插入语有一个窍门,就是在一个句子中,如果有这种情况：“···,.,····”两个逗号之间的都是插入语.例：He is,I think ,the best student in the class."I think "就是插入语.（插入语就是在英语句子插入一个与全句句义无直接关系的附加部分）再举一个例子：When do you think he will be back （试比较：When will he be back ）“do you think”是插入语.
答案选C .经过以上分析很明显,carried out也是修饰the plan.言下之意,这个句子一共有两个修饰语修饰the plan.