Explanation/Reference: https://docs.splunk.com/Documentation/SplunkCloud/8.0.2003/Search/Usethesearchcommand

Explanation
The correct answer is D. limit=0. This is because the limit argument specifies the maximum number of series to display in the chart. If you set limit=0, no series filtering occurs and all values are returned. You can learn more about the limit argument and how it works with the agg argument from the Splunk documentation1. The other options are incorrect because they are not valid values for the limit argument. The limit argument expects an integer value, not a string or a wildcard. You can learn more about the syntax and usage of the timechart command from the Splunk documentation23.