Explanation: According to the Salesforce documentation, the first step the user must take in order to change which email template is used in a running engagement program is to pause the program. A running engagement program is a program that is actively sending emails and performing actions to the prospects in the program. To make any changes to a running program, such as changing the email template, the user must first pause the program to stop the email sends and actions. After making the changes, the user can resume the program and continue the email sends and actions. Copying the original engagement program, changing the wait time for the template, or deleting the old sent email are not the first steps the user must take, as they will not allow the user to change the email template in the running program.