Correct Answer:
B. Very happy
The idiom "on cloud nine" describes a state of extreme happiness, joy, or elation. When someone is "on cloud nine," they are feeling incredibly pleased and delighted, often after receiving good news or experiencing a positive event. The phrase evokes a sense of floating high above the ground, symbolizing immense joy. It does not mean sad, confused, or angry. For instance, a person who just got engaged or received a promotion might be described as being "on cloud nine." This idiom is widely used to express profound contentment.