Which search would return events from the access_combined sourcetype?

The search that would successfully return events from the access_combined sourcetype is clearly defined by the case sensitivity of the sourcetype name in Splunk. In this context, the correct choice is the one that uses the precise casing expected by Splunk. The correct syntax must match the exact way the sourcetype is stored in Splunk's configurations, which is "access_combined".

In Splunk, sourcetype is case-sensitive, meaning that any variation in capitalization would cause the query to not match the actual sourcetype name. Therefore, using lowercase 'sourcetype' aligns with Splunk's requirement for sourcetype searches because it presents the name exactly as it is meant to be referenced.

Options with capitalized first letters or entirely in uppercase do not match the expected value of the sourcetype, leading to the inability to retrieve the intended events. Therefore, it is critical to adhere to the correct case in the search for successful data retrieval within Splunk.

Thus, the use of lowercase for 'sourcetype' followed by the correctly spelled and cased 'access_combined' ensures that the search will yield the desired results from that specific sourcetype.