An online retailer wants to study whether more lenient return policies increase purchasing behaviors. They select a random sample of 2000 customers who have made purchases in the past year.
They use a random number generator to select 1000 customer account numbers to assign to the treatment
group. The remaining 1000 customers are assigned to the control group.
What type of experiment design is this?

A) randomized block
B) stratified
C) completely randomized
D) marched pairs
E) cluster