Answer:
See explanation below
Step-by-step explanation:
Explanation of the course of effects:
A: The density of the people during the pandemic increased the amount of cases that came.
B: So the people wear face masks to prevent themselves from ending up with the virus
C: To further prevent the virus, people are spread 6 feet apart, to minimize the aerial transfer of the virus.
D: The doctor writes down the people who are getting the vaccine, the strongest defense against the virus.