Search results are processed, created, and written to the itsi_summary index via an alert action.
Reference: https://docs.splunk.com/Documentation/ITSI/4.10.2/SI/BaseSearch
D is the correct answer because KPI search results are stored in the itsi_summary index in ITSI. This
index is an events index that stores the results of scheduled KPI searches. Summary indexing lets you
run fast searches over large data sets by spreading out the cost of a computationally expensive report
over time. Reference: Overview of ITSI indexes