Answer:
The sentence above is a compound sentence.
Step-by-step explanation:
A compound sentence joins two or more independent clauses with a coordinator such as and, for, but, or a semicolon. Independent clauses can stand alone as a sentence because they represent a complete thought. The sentence above is made up of two independent clauses linked by the coordinator and (1,2).
1) Many plants survived the eruption of Mt. St. Helens
2) Their presence brought deer back to the area