Option A) "The rhinoceros lowered its head and charged" is a single sentence since it does not have any coordinating or subordinating clauses. It has a subject (the rhinoceros) and a predicate (lowered its head and charged).
Option B is a compound sentence since it has two independent clauses that are joined by a coordinating conjunction (and)
Option C) is also a compound sentence since it has two independent clauses joined by a semicolon.
So the correct option is A)