You work as a Network Administrator for Tech Perfect Inc. The company has a Windows Server 2008 Active Directory-based single domain single forest network. The functional level of the forest is Windows Server 2008. The company's headquarters is located at Los Angeles. A branch office of the company is located at Denver. You are about to send a message to Rick who is a Network Administrator at Denver. You want to ensure that the message cannot be read by anyone but the recipient. Which of the following keys will you use to encrypt the message?