Hello. You did not enter the protocols to which this question refers, which makes it difficult to come up with an exact answer. However I will try to help you in the best possible way.
To create reminders about the use of the mask, you must spread posters, or even post-its in easy to see places, where all the people who will execute the protocols will be able to see.
These posters should have, in a striking way, information about the obligation of the mask and the dangers that can be presented if it was not used.
It's c.
A. 42 1/2 pounds is way over. And if if she picked 4 1/4 pounds for $10, then your answer will be less than a 4 1/4.
B. It's too high, maybe for money it may work but not for a dollar.
C. It's the only that makes sense, and I did my work on paper and it is C.
D. It's way too high, just like B.