What command will successfully start the mongod daemon with all default settings as a background...

The --fork option starts mongod in daemon mode so the server process continues in the background. When --fork is used, MongoDB requires diagnostic output to be redirected through a logging destination such as --logpath or --syslog; the process cannot simply detach while continuing to use the normal foreground output stream. Option C supplies both --fork and a valid log path, while leaving the other server settings at their normal defaults unless they are configured elsewhere. Option A explicitly sets the default port but does not satisfy the logging requirement associated with --fork. Option B treats the literal word default as a filesystem path and does not provide the required log destination. Option D uses an unsupported --default switch. In production, MongoDB packages commonly use service managers such as systemd, and a configuration file is usually preferred over manually launching mongod with a long list of command-line options. Nevertheless, among the commands shown, C is the one that correctly daemonizes the server process and provides the logging configuration required for a successful fork.

Study Guide reference/topic:MongoDB Architecture and Core Operations - mongod startup, background execution, logging, and server configuration.

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