• Sieve Mesh Specifications for Nematode Extraction:
• Mesh Opening Dimensions: Sieve mesh ratings define the number of wires per linear inch:
• 60 mesh: $\sim 250\,\mu\text{m}$
• 100 mesh: $\sim 150\,\mu\text{m}$
• 200 mesh: $\sim 75\,\mu\text{m}$
• 300 mesh: $53\,\mu\text{m}$ ($53\text{u}$) aperture opening, widely used to retain smaller juveniles and vermiform nematodes while discarding silt.
• 350 mesh: $\sim 45\,\mu\text{m}$
• 400 mesh: $\sim 38\,\mu\text{m}$
• Conclusion: The aperture size in a 300 mesh sieve is $53\,\mu\text{m}$ (Option 1).

Correct option: (1) 53y