Fact 1: Television advertising is becoming less effective: the proportion of brand names promoted on television that viewers of the advertising can recall is slowly decreasing. Fact 2: Television viewers recall commercials aired first or last in a cluster of consecutive commercials far better than they recall commercials aired somewhere in the middle.
Fact 2 would be most likely to contribute to an explanation of fact 1 if which of the following were also true?
Option (D)
Because D indicates that the number of commercials in a cluster is increasing, it entails that proportionally more commercials are aired in intermediate positions. Hence, D helps fact 2 explain fact 1 by showing that increasingly more commercials are aired in positions in which viewers find them difficult to recall. D is the best answer. A testifies to the ineffectiveness of television advertising but does not help fact 2 explain fact 1. B indicates that fact 2 contradicts rather than explains fact 1, since it suggests that the number of commercials per cluster is decreasing. C help to explain fact 1-by describing a change in viewing habits and a change in programming-but neither relates fact 2 to fact 1.