Humans have introduced alien species into the environmentin all these ways except .......

Options

A. genetic engineering
B. human colonization of new areas
C. horticulture and agriculture
D. accidental transport

Answer

**Step-by-Step Solution:**

1. **Understanding Alien Species**: Alien species, also known as exotic species, are organisms that are introduced to a new environment where they are not native. This can happen through various human activities.

2. **Analyzing the Options**: The question asks which of the listed methods is NOT a way humans have introduced alien species into the environment. We need to evaluate each option carefully.

3. **Option 1 - Genetic Engineering**: Genetic engineering involves altering the genetic makeup of organisms to create new traits or eliminate diseases. This process does not involve the introduction of alien species into the environment but rather modifies existing species. Therefore, this option does not fit the criteria of introducing alien species.

4. **Option 2 - Human Colonization of New Areas**: When humans colonize new areas, they often bring along various species (plants, animals) that are not native to those areas. This can lead to the introduction of alien species. Hence, this option does involve the introduction of alien species.

5. **Option 3 - Horticulture and Agriculture**: The practice of horticulture and agriculture often involves the cultivation of non-native plants and animals, which can lead to the introduction of alien species into the environment. Thus, this option also involves the introduction of alien species.

6. **Conclusion**: Based on the analysis, the correct answer is that genetic engineering is the method through which humans have NOT introduced alien species into the environment.

**Final Answer**: Genetic engineering.

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