The correct answer is 3. The new electric pencil sharpener does not sharpen well; I prefer the old manual one.
Explanation:
In writing, combining two sentences implies creating a new longer or more complex sentence with the information provided in two different sentences, in most cases, this can be done by using certain transition words such as and, but, etc. or through the use of punctuation marks. In the case of punctuation marks two complete sentences or independent clauses that express a complete idea can only be combined using a semicolon (;) because the use of a comma (,), colon (:) or other punctuation marks is not correct for linking two independent clauses. According to this and considering the sentences presented are independent clauses or complete sentences because each of them expresse a complete idea, these should be combined using a semicolon and therefore the correct way to combine them is "The new electric pencil sharpener does not sharpen well; I prefer the old manual one".
