Final answer:
The sentence is a compound-complex sentence.
Step-by-step explanation:
The sentence 'Even though my sister is the biggest pest in the world, my mom still says I have to take her to the park with me' is an example of a compound-complex sentence.
It is a compound-complex sentence because it has both a compound element (the two independent clauses 'Even though my sister is the biggest pest in the world' and 'my mom still says I have to take her to the park with me') and a complex element (the dependent clause 'Even though my sister is the biggest pest in the world').
Compound-complex sentences combine two or more independent clauses (compound) with one or more dependent clauses (complex).