Understanding the Question
The question asks for a noun that describes a round, yellow fruit. Each option presents a different kind of fruit, and it’s essential to analyze each one to find the correct answer.

Analyzing the Options
- Option A: Orange
- Oranges are round and typically orange in color, not yellow. Therefore, this option does not fit the description.
- Option B: Apple
- Apples can be red, green, or yellow, but they are not typically round in the way the question specifies. Most apples are more round than yellow, which makes this option incorrect.
- Option C: Banana
- Bananas are long and curved, not round, making this option unsuitable for the description of a round fruit.
- Option D: Grapes
- Grapes are small and can be green or purple, but they are not yellow or round in the way a fruit like a lemon or a grapefruit would be.

Correct Answer: Lemon
The correct answer should actually be "Lemon," which is round and yellow, but none of the options provided in the question accurately represent this fruit. If you need to choose the closest match from the given options, none are fully correct, but it’s important to note that "banana" does not fit the description of roundness.

Conclusion
In summary, while the answer indicates "C" (Banana), it does not accurately represent a round yellow fruit. The best example of a round yellow fruit, which should have been included, is the lemon. Always ensure to analyze all options thoroughly to arrive at the correct answer.