When I visit my mother, I eat cookies.

Explanation

The sentence "When I visit my mother, I eat cookies" is a complex sentence because it:- Has an independent clause (I eat cookies)- Has a dependent clause (When I visit my mother)- The dependent clause is introduced by a subordinating conjunction (When)The sentence can be broken down into:- Independent clause: "I eat cookies" (stands alone as a complete sentence)- Dependent clause: "When I visit my mother" (cannot stand alone as a complete sentence)- Subordinating conjunction: "When" (connects the dependent clause to the independent clause)Complex sentences have a main clause and a subordinate clause, and this sentence fits that structure.