Adding -s is the most common. for example: books, cups, pencils, etc. -es might have been the one that confused you, but that isn't a super common ending for plurals--instead, a more common one would be "-ies" which is when you drop the y (berry becomes berries, for example).
Answer:
I am very confuzoled by this I don't wanna say question so statement
<u>The correct answer is A.</u> The diseases we immunize against are not gone and they are still deadly. These diseases still exist in many places in the world. Polio was eliminated from the United States thanks to vaccination, it still occurs in Afghanistan, Pakistan and Nigeria, being a serious problem there. If we do not get vaccinated this type of disease can return to the country.
I'm pretty sure it would be A.