This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thorax, Subject name: Anatomy
Which of following is attached to first rib? 
Select and explain. 
A. Scalenus posterior, B. Serroatus posterior superior, C. Scalenus medius, D. None of the above
C: Scalenus medius
Answer: C: Scalenus medius 
Explanation: Scalenus mediums attached to the first rib. B D CHOURASIAS HUMAN ANATOMY UPPER LIMB THORAX VOLUME, 1 SIXTH EDITION, Page no,199