Based on the options provided, the most reasonable conclusion that a reader could draw—assuming the selection discusses risk factors related to 2019-nCoV (the virus responsible for COVID-19)—is:
A) Some people are at a lower risk of being infected by 2019-nCoV.
This conclusion is broad enough to encompass various factors that might contribute to differing levels of risk among individuals. The other options are either too specific or factually incorrect.