The comma rule used in the sentence is the comma used to separate clauses in a compound sentence.
The comma rule used in the sentence is the comma rule for introductory phrases.
The comma rule used in the sentence is the comma used to separate independent clauses joined by a coordinating conjunction. In this case, the coordinating conjunction used is "for", which connects the two independent clauses "We are excited for summer vacation" and "we have plans to visit several national parks."
