Pollsters Use Random Digit Dialing to Gather National Samples for Surveys

Pollsters use random digit dialing to gather national samples for surveys because

A) sampling errors are typically too low when other techniques are used.
B) sampling errors are typically too high when other techniques are used.
C) there is not a complete list of all Americans that can be used to identify the population.
D) it is the only method that generates high levels of measurement error.