B) Pseudocoelomate

Pseudocoelomate refers to an intermediate body cavity between the mesoderm and endoderm in some animals. However, flatworms do not have a pseudocoelom, making option B the correct answer.

To understand this better, let's break down the features of flatworms and why they do not possess a pseudocoelom.

Bilateral Symmetry:
- Flatworms exhibit bilateral symmetry, meaning their body can be divided into two equal halves along a single plane.
- This symmetry allows for efficient movement and coordination of body parts.

Dorsiventrally Flattened:
- Flatworms have a dorsoventrally flattened body shape, which means they are flattened from top to bottom.
- This adaptation allows them to live in narrow spaces, such as the spaces between sand grains or under rocks.

Triploblastic:
- Flatworms are triploblastic, meaning their body is composed of three germ layers: ectoderm, mesoderm, and endoderm.
- The ectoderm gives rise to the outer covering of the body, the mesoderm forms muscles and other organs, and the endoderm lines the gut and associated structures.

Pseudocoelomate:
- A pseudocoelom is a body cavity that is not fully lined by mesoderm tissue.
- It is found in animals like roundworms (nematodes) and rotifers.
- Flatworms, on the other hand, do not have a pseudocoelom. Their body cavity is known as an acoelom, which means it lacks a fluid-filled cavity between the body wall and the gut.

In conclusion, while flatworms possess bilateral symmetry, are dorsiventrally flattened, and are triploblastic, they do not have a pseudocoelom. This makes option B, "Pseudocoelomate," the correct answer.

Flatworms are Acoelomate.. they lack body cavity called coelom..there is complete absence of mesodermal layer or u can say semi-solid mesodermal tissues between the gut and body wall hold their organs in place...

whereas Pseudocoelomate have a false cavity.. the mesoderm is partly lined or scattered in which internal organs are held in place loosely..for eg Roundworms..