The Young Children’s Charity of Eastern Canada would like an accurate estimate of how much it ...

The Young Children’s Charity of Eastern Canada would like an accurate estimate of how much it costs to raise a child between the ages of 2 and 12 each year for its fundraising campaign. The organization hired you to find out how much households spent on raising a child in 2011. The charity gave you a list of four million residential telephone customers in the area. You sampled every four-thousandth address on the list. You survey each sampled household by telephone.
In this study, each residential telephone customer is your
A) sampling frame.
B) observation unit.
C) sampling element.
D) sampling unit.
E) sampling interval.