A. You can modify the search string in the panel, and you can change and configure the visualization.
B. You can modify the search string in the panel, but you cannot change and configure the visualization.
C. You cannot modify the search string in the panel, but you can change and configure the visualization.
D. You cannot modify the search string in the panel, and you cannot change and configure the visualization.
Explanation:
Reference: https://docs.splunk.com/Documentation/Splunk/7.2.6/Viz/WorkingWithDashboardPanels