The Fact That Some People in the United States May

The fact that some people in the United States may not have a telephone or only have a cell phone or refuse to participate in polls illustrates what about scientific polling?

A) Pollsters can overcome any problems with the sample to make sure the results are not biased.
B) Nothing really because these people constitute a very small part of the population.
C) No poll is completely free of the biases they introduce in drawing the sample.
D) There is really no such thing as scientific polling and these problems make polls unreliable.