Which of the following are valid expressions for specifying a time range?

The option chosen is valid because specifying a time range in Splunk often requires defining the start time and/or the end time for the data being queried. The expression "earliest=" is specifically used to indicate the starting point of the time range. When setting a time filter in a Splunk search query, using "earliest=" allows the user to filter the data to include only events that occurred after a specific date and time, which is crucial for extracting relevant information.

Other expressions related to time range specification, such as "latest=" and "end=", serve to indicate the endpoint of the time range—this means that while they are also valid expressions, they do not directly address the necessity for defining the start time, which is often the first step in filtering data. The "start=" expression can also be seen in this context, but conventionally in Splunk, "earliest=" is used more commonly for this purpose. Therefore, in cases where you need to establish a starting point in your queries, "earliest=" is particularly significant and widely recognized in Splunk search practices.