The disadvantage of using common names for species is that:

Options

A. the names may change
B. one name does not apply universally
C. one species may have several common names and one common name may be applied to two species
D. all of the above

Answer

**Step-by-Step Solution:**

1. **Understanding Common Names**: Common names are the names used by the general public to refer to species. They can vary significantly from one region to another.

2. **Variability of Common Names**: One of the main disadvantages of using common names is that they can differ from place to place. For instance, the same species may be called different names in different countries or even different regions within a country.

3. **Lack of Universality**: Because common names are not standardized, a single species may have multiple common names. This lack of a universal name can lead to confusion in communication, especially in scientific contexts.

4. **Multiple Common Names for One Species**: A single species can be known by several common names. For example, the plant known as "dandelion" in English may have different names in other languages or regions.

5. **One Common Name for Multiple Species**: Conversely, a single common name may refer to more than one species. This can lead to misunderstandings, as people may think they are talking about the same organism when they are not.

6. **Conclusion**: Due to these reasons, the use of common names can create confusion and miscommunication in the scientific community. Therefore, the best practice is to use scientific names, which are standardized and universally accepted.

**Final Answer**: The disadvantages of using common names for species include variability in names across regions, lack of universality, multiple common names for a single species, and one common name being used for multiple species. Thus, the answer is "all of the above."

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