Q.Choose the wrong statement among the following:

Step 1. Check statement (a). In the earthworm, the male genital pore is indeed single and median, located mid-ventrally on the 18th segment. This statement is correct.

Step 2. Check statement (b). Setae (small S-shaped chitinous bristles embedded in pits of the body wall) grip the substratum and, working with the muscles, enable the peristaltic locomotion of the earthworm. This statement is correct.

Step 3. Check statement (c). The body wall of the earthworm actually contains two layers of muscle beneath the epidermis: an outer layer of circular muscles and an inner layer of longitudinal muscles. Alternate contraction of these two layers (circular muscles making the body thin and long, longitudinal muscles making it short and thick) produces the peristaltic waves used for burrowing and movement. Saying the muscular layer is made up of "only circular muscles" is therefore false — this is the wrong statement. …

Evaluate each statement against known earthworm anatomy (reproductive pores, setae function, body-wall musculature, and intestinal typhlosol …

• Assuming only one muscle layer exists because earthworms appear externally smooth and simple
• Confusing the outer circular and inner longitudinal muscle layers, or thinking only longitudinal muscles are present …