Your network contains an Active Directory forest. The forest contains two domains named contoso.com and nwtraders.com.You have a DNS server named DNS1. DNS1 hosts Active Directory-integrated zones for contoso.com and nwtraders.com.You discover that client computers in contoso.com cannot use single-label names to access servers in nwtraders.com.You need to ensure that contoso.com computers can access nwtraders.com servers by using single-label names.What should you modify？（）

A. the DNS suffix search order on DNS1
B. the DNS suffix search order on the client computers
C. the root hints servers on DNS1
D. the security settings of the nwtraders.com zone