In which sentence is the comma correctly placed? He was tired, so he took a nap., He was tired so, he took a nap., He was tired so he took, a nap., He was, tired so he took a nap.

In which sentence is the comma correctly placed? He was tired, so he took a nap., He was tired so, he took a nap., He was tired so he took, a nap., He was, tired so he took a nap.

Explanation

He was tired, so he took a nap.

A comma is needed before "so" when it connects two independent clauses.