Which of the following is not characteristic of the animal kingdom?

Options

A. Multicellularity, cells form tissues and organs
B. Exclusive reliance on sexual reproduction
C. Motility at some stage of the life cycle
D. Embryonic development during the life cycle

Explanation

To determine which of the following is not a characteristic of the animal kingdom, we will analyze each option provided in the question:

1. **Multicellularity**: Animals are predominantly multicellular organisms. They are composed of more than one type of cell, which are organized into tissues and organs. This is a fundamental characteristic of the animal kingdom.

2. **Tissue and Organ Formation**: Animals exhibit various levels of organization, including cellular, tissue, organ, and organ system levels. This means that cells form tissues, and tissues form organs, which is indeed a characteristic of animals.

3. **Exclusive Reliance on Sexual Reproduction**: This statement suggests that animals can only reproduce sexually. However, many animals, especially in lower phyla such as Porifera (sponges) and Cnidaria (like hydra), can reproduce asexually as well. Therefore, this statement is not true for all animals and is the correct answer to the question.

4. **Motility at Some Stages of the Life Cycle**: Most animals have the ability to move at some point in their life cycle. While some lower animals may be sedentary, motility is a common characteristic of the animal kingdom.

5. **Embryonic Development During the Life Cycle**: Animals undergo embryonic development, where tissues and organs develop from embryonic germ layers (ectoderm, endoderm, and mesoderm). This is a characteristic of animals.

Based on the analysis, the option that is not a characteristic of the animal kingdom is **"exclusive reliance on sexual reproduction."**

### Summary of the Solution:
- **Step 1**: Identify the characteristics of the animal kingdom.
- **Step 2**: Analyze each option provided in the question.
- **Step 3**: Determine which option does not apply to all animals.
- **Step 4**: Conclude that "exclusive reliance on sexual reproduction" is not a characteristic of the animal kingdom.