[1] The twins had opposite natures: the right-handed twin was truthful, and the left-handed twin was deceitful. [2] The right-handed twin always did the right thing, and the left-handed twin always did everything backward. [3] In these ways, the brothers represented the two warring natures that are in all people. [4] Quarreling constantly, they used magical powers to create animals that fought one another, and to create plants and medicines that could be used for good or for evil.

Is this a run-on sentence, simple sentence, compound sentence, or compound-complex sentence?

thank you for the help!

Option C. Sentence number 2 "The Right-handed twin always did the right thing, and the left-handed twin always did everything backward." is a compound sentence.

Explanation:

A compound sentence is a sentence that has a least two independent clauses that are joined by a comma, semi-colon, or a conjunction such as the word "and". An independent clause is a clause that has a subject and a verb and that forms, by itself, a complete thought. The sentence "The right-handed twin always did the right thing, and the left-handed twin always did everything backward" is an example of a compound sentence as it has two independent clauses that make a complete thought by themselves ("the right handed twin always did the right thing) (The left-handed twin always did everything backward) that are joined to each other using a comma followed by the conjunction "and".