Final answer:
The given sentence, 'I don't read many nonfiction books, but I love to read biographies,' is a compound sentence.
Step-by-step explanation:
The given sentence, 'I don't read many nonfiction books, but I love to read biographies,' is a compound sentence. A compound sentence consists of two or more independent clauses joined by a coordinating conjunction (such as 'but' in this case) or a semicolon (;). Each independent clause can stand alone as a separate sentence. In this sentence, the two independent clauses are 'I don't read many nonfiction books' and 'I love to read biographies.'