Which feature distinguishes Enterobius vermicularis eggs from Trichuris trichiura eggs?

• A. Small oval with a flattened side
• B. Barrel-shaped with polar plugs
• C. Spherical with a single operculum
• D. Oval with a thick mamillated shell

Answer: (A)

The feature being tested is how the eggs look under the microscope, which helps distinguish common intestinal nematodes by shape and surface. Enterobius vermicularis eggs are characteristically small and oval with one side flattened. That flattening is a distinctive, recognizable cue for pinworm eggs.

In contrast, Trichuris trichiura eggs are barrel-shaped with polar plugs at each end, a different and easily mistaken but clearly different morphology. The other descriptors describe eggs of different parasites (for example, operculum-bearing spherical eggs or eggs with a thick mamillated shell) and do not match Enterobius morphology. So the flattened oval shape is the best identifying feature for Enterobius eggs.