Which aspect of an email includes the "CC" field and subject line?

The aspect of an email that encompasses the "CC" field and subject line is the email header. The header provides essential information about the email, including the sender, recipient, subject, and carbon copy (CC) information. This information is crucial for understanding the context of the email before reading the content.

The subject line succinctly summarizes the email's topic, allowing recipients to prioritize their reading, while the "CC" field indicates other individuals included in the conversation, ensuring transparency and clarity in communication. Each of these components is integral to how the email is structured and functionally operated, making the email header the correct choice in this scenario.