All of the us who have suffered the ill effects of common cold or 'flu' it is caused by

Answer

**Step-by-Step Solution:**

1. **Identify the Illness**: The question refers to the common cold and flu, which are both respiratory illnesses that many people experience.

2. **Determine the Causative Agent**: The common cold and flu are caused by a specific type of organism. In this case, it is important to identify that these illnesses are primarily caused by viruses.

3. **Understand the Nature of Viruses**: Viruses are unique organisms that do not fit into the traditional five kingdom classification system. This is because they are not considered true living organisms. They lack cellular structure and cannot carry out metabolic processes independently.

4. **Explain Virus Characteristics**: Viruses are non-cellular and have an inert crystalline structure when outside a host cell. They require a living host cell to replicate and propagate. Once inside a host, they hijack the host's cellular machinery to reproduce.

5. **Conclude the Answer**: Therefore, the correct answer to the question is that the common cold and flu are caused by viruses.

**Final Answer**: The common cold and flu are caused by viruses.

---