The first fact: the effectiveness of TV advertising is getting worse and worse. A tracking survey shows that among the various products launched by TV advertising, the percentage of products that viewers can remember their brand name decreases year by year. The second fact: In a continuous TV commercial, the first and last impressions of the audience are more impressive, and the impressions of the ads broadcast in the middle are generally much shallower. Which of the following, if true, can make the second fact a reasonable explanation of the first fact? ['In recent years, the average time allowed for continuous advertising in TV shows has gradually decreased.', 'In recent years, the average time people spend watching TV has gradually decreased.', 'In recent years, the average time taken by a continuous TV commercial has gradually increased.', 'In recent years, the average number of advertisements appearing in a continuous TV commercial has gradually increased.']