On the rough draft of her essay, Anna wrote:

Columbus found valuable resources in the New World, many explorers came to the area after him.

What common mistake did Anna make when writing this run-on sentence?
Select one:

She arranged the dependent clause in front of the comma and the independent clause.

She joined two independent clauses with only a comma.

She used a confusing pronoun that had no antecedent.

She used verbs that do not agree in verb tense.