Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word that best fits each of the numbered blanks.

The USA is encouraging Americans to wear face masks. There have been a lot of talks about whether or not face masks are effective in helping slow down the ___(1)___ of the COVID-19 coronavirus. The government is set to encourage Americans to use homemade face covering like cloth masks, bandanas and scarves. At first, the WHO and ___(2)___ health organizations recommended drat people who were not sick didn't need to wear masks or cover their faces. ___(3)___, it is now proved that face masks can work effectively. They point to countries like Singapore and South Korea, ___(4)___ people wear masks and reported infection rates are lower.