This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: NEET 2019, Subject name: Physiology
All are true about Decerebrate posture except:- 
Select and explain. 
A. Extension of both upper and lower extremity, B. Flexion of upper extremity and extension of lower extremity, C. Exaggerated gamma motor neuron discharge, D. Reticulo spinal tract is also involved
B: Flexion of upper extremity and extension of lower extremity
Answer: B: Flexion of upper extremity and extension of lower extremity 
Explanation: Decerebrate rigidity: When brain stem of animal is sectioned below midlevel of mesencephalon but pontine & medullary reticular systems as well as vestibular system are intact, this is decerebrate animal This results in rigidity of antigravity muscles a muscles of neck & trunk & extensors (i.e all extensors go into spasm) This decerebrate rigidity is due to blockage of normally strong input to medullary reticular nuclei from cerebral coex, Red nuclei & the basal ganglion. Lacking this input, medullary reticular inhibitor system becomes nonfunctional, full overactivity of pontine excitatory system occurs & rigidity develops. (Due to exaggerated gamma motor neuron discharge) Decoicate rigidity: Thick layer of coex is removed & all other structures are preserved. This results in decoicate rigidity a flexors of upper limb & extensors of lower limb goes into spasm (flexion).