Fill in the blanks with the correct option: A person cannot read or write.

The question asks for a word describing a person unable to read or write. Understanding prefixes is key here.

• Illiterate is the correct answer. The prefix 'il-' means 'not', so 'illiterate' means 'not literate', or unable to read and write.
• Illegible (A) refers to writing that cannot be read due to poor handwriting, not the person's ability.
• Legible (B) means clear enough to be read.
• Literate (C) means able to read and write, which is the opposite of what the question describes.

Therefore, 'illiterate' accurately describes a person who cannot read or write.