Look at the picture and choose the correct option that should be in capital letter.

Do you know who is ronaldo?

The correct answer is: Ronaldo

Here, Ronaldo should be written with capital letter, because it is a noun. Noun should always capitalized. No matter where it comes in the sentence. Whereever it comes, it should be capitalized. Here, Ronaldo comes at the last yet it should be capitalized since it denotes to name of the person which is a noun.