Which form correctly shows the plural of the letter I?

Which form correctly shows the plural of the letter I?

• A. Is
• B. I'Ss
• C. Is
• D. I's

Answer: (D)

When you pluralize a single letter, you usually add an s, and an apostrophe is used when the letter form could be mistaken for a word. The letter I is also the pronoun I, so writing it as Is would read as the verb “is.” Writing I's makes it clear you’re referring to multiple instances of the letter itself, not the pronoun or the verb. That apostrophe helps avoid confusion and follows the standard convention for pluralizing a letter name. The other spellings read as ordinary words or introduce an unnecessary extra character, so they aren’t correct.

When you pluralize a single letter, you usually add an s, and an apostrophe is used when the letter form could be mistaken for a word. The letter I is also the pronoun I, so writing it as Is would read as the verb “is.” Writing I's makes it clear you’re referring to multiple instances of the letter itself, not the pronoun or the verb. That apostrophe helps avoid confusion and follows the standard convention for pluralizing a letter name. The other spellings read as ordinary words or introduce an unnecessary extra character, so they aren’t correct.