Which of the following investigations would most effectively show that masks protect against coronavirus transmission?Multiple ChoiceCompare the incidence of COVID among a sample of middle-aged people from New York City who wear masks and either do or do not practice social distancing behaviors.Compare the incidence of COVID among a sample of older adults who wear masks and either live in New York City or live in rural New York communities.Compare the incidence of COVID among a sample of schoolchildren who wear masks to the incidence of COVID among older adult churchgoers who do not wear masks.Compare the incidence of COVID among individuals employed at neighboring New York City office buildings, one of which enforces a mandatory mask policy.