Answer:
The sentence above is made up of an independent clause, then a dependent clause, then an independent clause.
Explanation:
The sentence above is a compound-complex sentence. A compound-complex sentence is made up of two independent clauses and one or more dependent clauses. The difference between an independent clause and a dependent one is that former can stand alone as a sentence because it represents a complete thought.
I) We were waiting outside because it was a nice day, and my sister came to meet us
II) We were waiting outside
III) *Because it was a nice day
IV) And my sister came to meet us
As you can see, II and IV are the independent clauses in the sentence. They can stand alone as complete sentences. On the contrary, III is a dependent clause. It depends on the main clauses to complete its meaning. Otherwise, it is ungrammatical (III).