Which option for the pam_ldap module specifies a file from which global settings can be read?

The pam_ldap module allows for the integration of LDAP (Lightweight Directory Access Protocol) for authentication and user information retrieval. To configure the settings for pam_ldap, the configuration is typically stored in a specific file, with the option that specifies a file from which global settings can be read being "config."

This "config" option is used to point to a configuration file that contains the global parameters necessary for the interaction between the PAM (Pluggable Authentication Modules) and the LDAP server. The settings within this file can include the LDAP server address, bind credentials, and search base, among other essential parameters for proper authentication.

Using "config" allows the pam_ldap module to read the global settings, ensuring that all relevant configurations are centralized and easily maintainable. This is particularly valuable in environments where multiple services depend on consistent configuration settings for accessing the LDAP directory.

In contrast, the other options either do not directly refer to a configuration file or specify settings that are not specifically aimed at global configurations, making "config" the most accurate answer for the question posed.