What is a common problem today that wasn't a large problem in the past?
high infant mortality

multiple contagious diseases with no treatments or cures

exposure to negative media content

all of the above

I believe the answer is: Exposure to negative media content

In the past, the amount of media company is really limited. Since the development of internet and social media, it become much more easier for people to get involved in medic content. Since it is really hard to monitor these content, a lot more people are exposed to negative or fake media content.