Your network consists of a single Active Directory domain. All servers run Windows Server 2003 Service Pack 2 （SP2）.A firewall separates the internal network from the Internet.  The firewall blocks all outbound traffic except for HTTP and SMTP traffic.You install a DNS server. The DNS server is configured to use the default root hints. You need to ensure that the DNS server can resolve the host names on the Internet.  Which port should you open on the firewall？（）

• A、53
• B、135
• C、500
• D、3389