To solve this question, the user needs to know the difference between singular and plural forms of verbs.

In the given sentence, the subject is "New Orleans," which is a singular noun. When using a singular noun as the subject, the verb should also be in its singular form. Therefore, the correct verb to use in this sentence is "ranks," which is the singular form of the verb "rank."

Option A, "rank," is incorrect because it is the plural form of the verb and does not agree with the singular subject.

Option B, "ranks," is correct because it is the singular form of the verb and agrees with the singular subject.

Option C, "None of the above," is incorrect because option B is the correct answer.

Option D, "Both a and b," is incorrect because option A is not a correct answer.

Therefore, the answer is: B. ranks.