Answer:
The underlined portion of the sentence is a Dependent Clause
Explanation:
A dependant Clause is one that can not state by itself to have a complete idea, it depends on a Main Clause to communicate something, "When my next-door neighbor fell and broke her hip" depends on the main clause since we do not know what happened to the next-door neighbor, besides one important characteristic of many dependant clauses is that they begin with a subordinating conjunction, in this case, the word "when".
