Concept:Electronic mail is sent to a specific recipient using that person's unique e-mail address.Explanation:To send an e-mail, the teacher must know the e-mail address of each student.An e-mail address looks like name@example.com.A website address is used to visit a webpage, not to deliver mail.A data file address and a modem address are not used for sending electronic mail.Therefore, the correct requirement is the recipient's e-mail address.Answer:C. E-mail address