Question

Earthworm has an unsegmented band called-
A. Clitellum.
B. Thorax.
C. Cephalothorax.
D. Metathorax.

Answer 1

As we knew that, earthworm is a reddish-brown terrestrial invertebrate that inhabits the upper layer of the moist soil. During day time, they live inside the burrows made by boring and swallowing the soil. In gardens, they can be traced by their fecal matter known as worm castings. The common Indian earthworms named are- Pheretima and Lumbricus. They have long cylindrical bodies. The body is divided into more than hundred short segments which are similar.

Complete Explanation:
Option A Clitellum: Clitellum is present in an earthworm’s body at the body region. A conspicuous dark band of glandular tissue termed clitellum covers segments in a mature worm. So, the earthworm has an unsegmented band in its body called clitellum. As a result, the body is divided into three distinct segments: preclitellar, clitellar, and postclitellar.
Option A is correct.
Option B Thorax: The prothorax, mesothorax, and metathorax are the three segments of the thorax of earthworms. Each segment has a pair of short legs. Thorax is the region between the abdomen inferiorly and the root of the neck superiorly. It forms the thoracic wall, its superficial structures and the thoracic cavity.
Option B is not correct.
Option C Cephalothorax: The cephalothorax, also known as the prosoma, is the most anterior of the body sections. The cephalothorax features eyes, mouth. The cephalothorax is more rigid than the abdomen and contains the muscles used to operate the limbs. Cephalothorax is present in arachnids.
Option C is not correct.
Option D Metathorax: Metathorax is the segment that bears the hindwings in most winged insects, though sometimes these may be reduced or modified as in flies, the metathorax is usually present in insects not in earthworm.
Option D is not correct.

Hence, Option A is the correct answer.

Note:
Hence, we discussed earthworm's unsegmented bands. Earthworms are known as friends of farmers because they make burrows in the soil and make the soil porous which helps in respiration and penetration of the developing plant roots. They're also utilized as game fishing bait. The process of increasing fertility of soil is known as Vermicomposting.