Which sentence option correctly uses a colon

A. When Ariana goes shopping, there is only one thing to do: plan to spend the whole day at the mall.

Explanation:

Use a colon to introduce an item or a series of items. Do not capitalize the first item after the colon (unless it's a proper noun). A capital letter generally does not introduce a word, phrase, or incomplete sentence following a colon. Avoid using a colon before a list if it directly follows a verb or preposition that would ordinarily need no punctuation in that sentence. When listing items one by one, one per line, following a colon, capitalization and ending punctuation are optional when using single words or phrases preceded by letters, numbers, or bullet points. If each point is a complete sentence, capitalize the first word and end the sentence with appropriate ending punctuation. Otherwise, there are no hard and fast rules, except be consistent. A colon instead of a semicolon may be used between independent clauses when the second sentence explains, illustrates, paraphrases, or expands on the first sentence. Capitalize the first word of a complete or full-sentence quotation that follows a colon. The colon lists what needs to be done. Basically, the sentence is stating that when Ariana goes shopping, the only thing to do is: spend the whole day in the mall. Do you understand what a colon is? A colon is a punctuation mark (:) used to precede a list of items, a quotation, or an expansion or explanation. A colon used in various technical and formulaic contexts, for example a statement of proportion between two numbers, or to separate hours from minutes (and minutes from seconds) in a numerical statement of time.

I hope this helps! :3 Have a great day!

one is a red flower, and one is the sky when the sun sets.