me and my fellow study mates are having a hard time with this question:

Which of the following sentences is punctuated correctly?
A. My brother the valedictorian of his high school got into a very competitive college.
B. The chili, which had been simmering on the stove for hours, made the whole house smell delicious.
C. My cat who is almost fifteen years old is getting a bit of gray fur around his nose.
D. That toy helicopter which broke after only a few days was actually quite expensive.

I think it is B but my study mates think it is C.
Can you help us?

It was correct!! Thank you!

However is still got a bad grade (66.67)
But if your answer was wrong it would be lower so thx alot

You're welcome.

Here are two websites to use when you're studying English -- whether grammar or punctuation or writing or whatever. These are excellent! Bookmark them for future use. =)

http://www.chompchomp.com/terms.htm
and
http://guidetogrammar.org/grammar/index2.htm

B is correct.

See #4 here:
http://guidetogrammar.org/grammar/commas.htm

Thank you so much! Have a fantastic rest of your day!

P.S. my study mates wanted to say thanks because now they see where they went wrong

Excellent!

And you're all welcome!

Of course, I'd be happy to help! Let's go through each option to identify the sentence that is punctuated correctly.

Option A: "My brother the valedictorian of his high school got into a very competitive college."
This sentence is missing proper punctuation. It should have a comma after the word "brother" to separate the description from the main clause. So, Option A is not punctuated correctly.

Option B: "The chili, which had been simmering on the stove for hours, made the whole house smell delicious."
This sentence is correctly punctuated because it uses commas to set off the nonessential phrase "which had been simmering on the stove for hours." Therefore, Option B is punctuated correctly.

Option C: "My cat who is almost fifteen years old is getting a bit of gray fur around his nose."
In this sentence, there are no commas to set off the nonessential phrase "who is almost fifteen years old." So, Option C is not punctuated correctly.

Option D: "That toy helicopter which broke after only a few days was actually quite expensive."
Similar to Option C, this sentence doesn't have commas to separate the nonessential phrase "which broke after only a few days." Hence, Option D is not punctuated correctly.

Therefore, the correct answer is Option B: "The chili, which had been simmering on the stove for hours, made the whole house smell delicious." It is the only sentence among the options provided that is punctuated correctly.