Please give me the correct answer.

Refer to interactive solution 17.45 to review a method by which this problem can be solved. the fundamental frequencies of two air columns are the same. column a is open at both ends, while column b is open at only one end. the length of column a is 0.504 m. what is the length of column b?

Me d is also an option but i couldn't get it in the picture

An entertainment firm offer serveral dj choices and light shows that range in price based on the rental time period. the djs cost between $219 and $369 per night and the light shows cost between $159 and $309 per night. if you are booking both a dj and a light show write a compound inequality that represents the possible total amount you would pay x