This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2018, Subject name: Ophthalmology
Obstacles in concomitant squint type is: 
Select and explain. 
A. Motor obstacles, B. Sensory obstacles, C. Central obstacles, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: CONCOMITANT SQUINT - type of manifest squint in which the amount of detion in the squinting eye remains constant in all directions of gaze, no limitation of ocular movements.. Any obstacles to the development of these processes result in concomitant squint . (1) Sensory obstacles -hinder the formation of a clear image in one eye. E.g. *Refractive errors*Prolonged use of incorrect spectacles*Anisometropia*Media opacities - Corneal/Lenticular opacities (2) motor obstacles - hinder the maintenance of eyes in the correct positional relationship in primary gaze or during ocular movements . E.g. - Congenital abnormalities of shape/size of the orbit*Abnormalities of extraocular muscles (3) central obstacles -*Deficient development of fusion faculty*Abnormalities of coical control of ocular movements as occurs in mental Trauma and hyperexcitability of CNS during teething.