Final answer:
A business email should include a recipient line, sender line, date, and subject. The email must be professional, with a clear subject line, and should be thoroughly proofread before sending.
Step-by-step explanation:
When crafting a business email, certain elements are essential to ensure that it meets professional standards. Based on the provided information, the required elements of a business email would be option 4): recipient line, sender line, date, and subject. This format reflects the importance of a clear and identifiable subject line to inform the reader of the email's content and provides a timestamp for the communication. Emails should always begin with a proper greeting using the receiver's appropriate title, be formatted with a concise and clear body, and end with a professional complimentary closing. Remember to make a good first impression with your email address, maintain a clear and meaningful subject line, and follow through with proofreading steps before sending to ensure that your message is error-free and well-received.