• Parotid Duct Opening in Ox: In cattle (Bos indicus / Bos taurus), the parotid salivary duct (ductus parotideus) opens into the buccal vestibule on the mucosal papilla salivalis directly opposite the upper 5th cheek tooth (upper second molar, $M_2$).

Correct option: (1) upper 5th cheek tooth

• ⚠️ Note: This question was officially DROPPED by NTA/ICAR in the final answer key because none of the four options provided the correct histological order. Full marks were awarded to all candidates.
• Histological Layers of the Retina (from Inner/Vitreous to Outer/Choroid):

• Internal limiting membrane
• Nerve fiber layer (stratum opticum)
• Ganglion cell layer
• Inner plexiform layer
• Inner nuclear layer
  6. Outer plexiform layer
  7. Outer nuclear layer
  8. External limiting membrane
  9. (B) Layer of rods and cones (photoreceptors)
  10. (E) Retinal pigment epithelium (RPE)
  • Why NTA Dropped This Question: The correct chronological sequence of the given five layers from inner to outer is (A) $\to$ (C) $\to$ (D) $\to$ (B) $\to$ (E). Because this correct sequence was completely missing among all four examination options, NTA cancelled the question.

• Location of the Myenteric Plexus: The Myenteric (Auerbach's) nerve plexus is situated between the inner circular and outer longitudinal smooth muscle layers of the Tunica Muscularis throughout the gastrointestinal tract.
• Function: Coordinates peristaltic motility and intestinal transit, distinct from the Submucosal (Meissner's) plexus.

Correct option: (4) Between two muscle layers of Tunica muscularis