Plants that don't have a well-differentiated body design are called ..............

Thallophytes

The correct answer is Option (3)- Thallophytes

Thallophytes are a group of plants characterized by a simple and undifferentiated body structure, lacking the distinct roots, stems, and leaves found in more complex plants. Instead of well-defined organs, thallophytes have a thallus, which is a flat or fleshy structure that serves various functions. This group includes several types of plants, such as algae, liverworts, and certain fungi.

Here's a brief explanation of the mentioned terms:

1. Algae: Algae are simple, autotrophic organisms that can range from unicellular forms, like Chlamydomonas, to multicellular forms, like seaweeds. They often have a thallus-like structure and can be found in aquatic environments.
2. Liverworts: Liverworts are non-vascular plants that belong to the division Marchantiophyta. They have a flattened, lobed thallus and are typically found in moist environments. Liverworts represent one of the earliest land plants.
3. Fungi: While fungi are not plants, some fungi, like certain molds, may also have a thallus-like structure. Fungi are a separate kingdom in the classification of living organisms, distinct from plants, animals, and bacteria.

Thallophytes are considered less advanced in terms of structural complexity compared to higher plants like gymnosperms and angiosperms. The absence of specialized tissues and organs in thallophytes reflects their primitive characteristics and evolutionary position in the plant kingdom.