Final answer:
The sentence given is a simple sentence because it contains a single main clause and expresses a complete thought on its own.
Step-by-step explanation:
The sentence "The presentation illustrates the problem." is a simple sentence. A simple sentence consists of a single main clause that has one subject and one predicate and can stand alone as a complete thought. Since there is only one main clause without any subordinate clauses or coordination with other clauses, it fits the criteria of a simple sentence.
A simple sentence has one main clause that expresses a single idea. In this sentence, the main clause is 'The presentation illustrates the problem.' It has a subject ('the presentation') and a predicate ('illustrates the problem').