The Gallup Poll has decided to increase the size of its random sample of Canadian voters from about 1500 people to about 4000 people. The effect of this increase is to: (a) reduce the bias of the estimate. (b) increase the standard error of the estimate. (c) reduce the variability of the estimate. (d) increase the confidence interval width for the parameter. (e) have no effect because the population size is the same.