You have a DNS server that runs Windows Server 2003 Service Pack 2 (SP2). The server contains two zones named nwtraders.com and contoso.com. Nwtraders.com is configured as an Active Directory-integrated zone. Contoso.com is configured as a standard primary zone. You discover that stale resource records are not being removed from contoso.com. Stale resource records are being removed from nwtraders.com. You need to ensure that stale resource records are automatically removed from contoso.com.  What should you do?（）  

• A、Enable aging and scavenging on the contoso.com zone.
• B、Convert contoso.com to an Active Directory-integrated zone.
• C、From the start of authority （SOA） record for contoso.com， change the refresh interval.
• D、From the start of authority （SOA） record for contoso.com， change the TTL For This Record value.