Final answer:
The correct sentence is: 'O Unless you are willing to work hard for your employer, you should not expect a promotion.'
Step-by-step explanation:
The item that uses correct grammar, punctuation, and connecting words is:
O Unless you are willing to work hard for your employer, you should not expect a promotion.
This sentence is correct because it uses the correct punctuation, using a capitalized 'O' at the beginning of the sentence, a comma before the clause 'unless you are willing to work hard for your employer,' and a period at the end. It also uses connecting words correctly to join the two independent clauses together.
Learn more about Grammar and punctuation in English sentences