When does Google Analytics sample data for reporting?

A. When the data you request has already been calculated in the aggregate tables
 B. When you create a report with metric and dimension combinations that have not been pre-aggregated and the report is based on data from a large number of visits
 C. When the report is pulled at the end of the high traffic week
D.  When you create a report with metric and dimension combinations that have not been pre-aggregated and the report is based on data from a small number of visits

Ans: B