This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Spinal Injuries, Subject name: Orthopaedics
The following X-ray was taken of a 50-year-old female with chronic backache. What is the most likely diagnosis? 
Select and explain. 
A. Spondylolysis, B. Spondylosis, C. Spondylolisthesis, D. Prolapsed inter-vertebral disc
C: Spondylolisthesis
Answer: C: Spondylolisthesis 
Explanation: (c)