During the development of most animals, cleavage leads to __________.

• A. the formation of the gastrula
• B. the formation of a multicellular blastula
• C. the differentiation of tissues
• D. the fusion of gametes

Answer: (B)

Verified step by step guidance

1. Understand the concept of cleavage: Cleavage is a series of rapid mitotic cell divisions that occur immediately after fertilization in most animals. These divisions increase the number of cells without increasing the overall size of the embryo.
2. Recognize the purpose of cleavage: The main goal of cleavage is to transform the single-celled zygote into a multicellular structure, which is essential for further development.
3. Identify the result of cleavage: Cleavage leads to the formation of a blastula, which is a hollow, multicellular structure. This stage is crucial for subsequent processes like gastrulation.
4. Clarify why other options are incorrect: Cleavage does not directly lead to the formation of the gastrula (which occurs later during gastrulation), tissue differentiation (which happens later in development), or the fusion of gametes (which occurs before cleavage).
5. Conclude the correct answer: The correct result of cleavage is the formation of a multicellular blastula, as this is the immediate outcome of the process.