Choose the sentence that is punctuated correctly.
O African bull elephants, for example, may weigh six to eight tons.
O African bull elephants; for example, may weigh six to eight tons.
The correct sentence is: "O African bull elephants, for example, may weigh six to eight tons."
Explanation: The first sentence is punctuated correctly. It uses a comma after the introductory phrase "O African bull elephants" and also correctly separates the phrase "for example" with commas. The information following the commas is a complete sentence, providing the weight range of African bull elephants.
The second sentence is not punctuated correctly. It uses a semicolon instead of a comma after the phrase "O African bull elephants". Semicolons are typically used to separate two closely related independent clauses or to separate items in a list where the items contain commas themselves. In this case, a comma is more appropriate to introduce the information that follows.