The phrase of the question "I bought a bunch of roses" is an informative phrase that describes an action and has an informal or casual connotation. While the phrase "I bought a bouquet of roses" like the previous one is a phrase that informs about an action, but has a different connotation because it uses a formal word like a bouquet, which gives it a formal connotation. Therefore, the correct answer is D. Bouquet of roses.
