Mike's radio is broken. He will have it repaired tomorrow. -Why don't you let Aunt Wang fix it? If she can't, no one can fix it. Have sb/sth done makes people do things, and the past participle and object are verb-object relations; Let someone do something. This structure omits the infinitive of to as the object complement, so D is chosen.
Comments: The usage of non-predicate verbs is relatively fixed, which is mainly distinguished by the relationship with the modified words. Generally, the present participle and the modified word are subject-predicate relations, while the past participle and the modified word are verb-object relations. The second is to show the difference of action state. The present participle indicates the ongoing accompanying action, the past participle indicates the passive action that has happened, and the infinitive indicates the specific action that will be carried out. Mastering these two points can basically solve this kind of problem.