Which of the following plants has an undifferentiated plant body and lacks vascular tissue?

Algae are large and diverse groups of simple, typically autotrophic organisms ranging from unicellular to multicellular forms. They are photosynthetic, like plants and are called 'simple' because they lack many distinct organs (like stem, leaves) found in land plants. Alga is a non-vascular plant, i.e. without a vascular system (xylem and phloem). Non-vascular plants have no roots, stems or leaves. Since each of these structures contains vascular tissues. Hence, the correct answer is algae.  Reason: Vascular tissue is a complex conducting tissue. The primary components of vascular tissues are xylem and phloem. These two tissues transport fluid and nutrients internally.