The correct option is this one - A complex sentence has one independent clause (a whole sentence) and one dependent clause (a partial sentence).
A dependent clause is a type of a clause which cannot stand on its own, but rather has to be included in a bigger sentence in order to make sense. Here, the dependent clause is Even though April began eating more fruits and vegetables. As you can see, this clause sounds incomplete, which is why it is joined with the independent clause she decided to continue drinking soft drinks in order to make sense.
