What is the first step you should follow to debug this problem?

After configuring PAM and NSS to integrate with OpenLDAP, the SSH server refuses to authenticate users who are only in LDAP.
What is the first step you should follow to debug this problem?

A.
Restart the pamd service.

B.
Restart the sshd service.

C.
Restart the nssd service.

D.
Add the Use_LDAP = yes parameter to sshd_config.