Which of the following contains the correct syntax for an allowed list in a monitored input?

The correct answer contains the syntax for an allowed list in a format that is recognized by Splunk for filtering monitored input data. In this case, option B reflects a simple yet effective approach by specifying a pattern that matches any filename ending with the ".log" extension. This is a common way to include files of a specific type without complicating the regular expression too much.

For the most part, regular expressions in this context work as a filter for inputs, allowing users to include or exclude certain logs. By expressing it as \.log$, you ensure that the condition matches log files that conclude with ".log". This is straightforward and effective for the intended purpose of monitoring.

On the other hand, options that present more complex or incorrect patterns do not align with the syntax rules or expected functionality. For instance, option A includes specific file names but also incorrectly uses the leading slash, while option C lacks the proper escaping for the dot, which could lead to mismatches, as the dot symbol in regex matches any character. Thus, the simplicity and correctness of option B make it the proper choice.