Final answer:
The sentence 'A trained dog's help could make independent living possible for a disabled person' is a simple sentence because it contains a single main clause without any additional main or subordinate clauses.
Step-by-step explanation:
The sentence in question, "A trained dog's help could make independent living possible for a disabled person," is a simple sentence. A simple sentence consists of one main clause that has a singular subject and predicate, and it can stand alone as a complete thought. This particular sentence has one main idea and does not contain any additional main or subordinate clauses, thus fitting the criteria of a simple sentence.