The correct answer is A. Simple sentence
.
A simple sentence must have a subject and a verb, express a complete thought, and only have one clause.
It is not a compound sentence because it doesn't have any conjunction or comma joining two independent sentences.
It is not a complex sentence because it only has one clause. A complex sentence has one independent clause and at least one dependent clause.
It is no a compound-complex sentence because it must have the characteristics above.
