There has been the introduction of online libraries and e-books
Explanation:
Over the last 20 years, technology has changed a lot. The introduction of the phone lead to online libraries and e-books. Also the rate of obesity ghastly increased since the introduction of fast food restaurants and fashion has been a big industry for many years.
I believe it is option "D.) The flu vaccine is not reliable enough to be worthwhile" It would have a negative impact on the economy due to people not spending money to have the flu vaccine.