This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Radiology
Flowing wax appearance on anterior and posterior borders of vertebrae with normal intervertebral disc space occurring due to ligament calcification is seen in – 
Select and explain. 
A. Ankylosing spondylitis, B. Diffuse idiopathic skeletal hypertrophy, C. Psoriatic spondyloarthropathy, D. RA
B: Diffuse idiopathic skeletal hypertrophy
Answer: B: Diffuse idiopathic skeletal hypertrophy 
Explanation: Diffuse idiopathic skeletal hyperostosis: DISH (hyperostotic spondylosis, Forestier's disease) is a multifocal entity of older people characterized by "flowing ossifications of the spine" involving four or more contiguous vertebrae and hyperostosis of some ligamentous attachments. The thick, flowing, florid, exuberant corticated plaques are extensive than that seen in degenerative changes producing so-called 'dripping candle wax or flowing candle wax' appearance.