For capital letters, we can just add the ending -s, for example:
I got As in the final exam.
for lower-case letters, an apostrophe is used to avoid confusion:
In the multiple-choice exam all the correct answers happened to be a's! (as in: option a)
Number one is Nonviolent protests.
Halloween love I and Carlotta
Answer:
The first reality show that followed the lives of a celebrity family whose last name was Jones.
