The Following Sentences Form a Paragraph

The following sentences form a paragraph. Proofread them for run-ons, comma splices, semicolon errors, relative pronoun errors, and -ING modifier errors. Identify the type of each error in each sentence, or select "correct" if the sentence is free of errors.
-According to experts, if logging in Mexican forests continues at recent levels; these wonderful butterflies will be extinct within twenty years.

A) correct
B) run-on
C) comma splice
D) semicolon error
E) relative pronoun error
F) -ING modifier error