Which of the following is not a benefit of transgenic animals ?

Options

A. Investigation of new treatments for diseases
B. Early detection of diseases
C. Testing the safety of vaccines
D. To produce useful biological products

Explanation

To determine which of the following is not a benefit of transgenic animals, we can analyze each option provided:

1. **Investigation of new treatment for diseases**: Transgenic animals are often used in research to study the effects of new treatments for various diseases. By modifying their genes, researchers can create models that mimic human diseases, allowing for the investigation of potential treatments. Therefore, this is a benefit of transgenic animals.

2. **Early detection of disease**: Early diagnosis of diseases typically relies on specific techniques such as PCR (Polymerase Chain Reaction) and ELISA (Enzyme-Linked Immunosorbent Assay). These methods are based on the amplification of DNA or the detection of specific antibodies, rather than on the use of transgenic animals. Hence, this option does not represent a benefit of transgenic animals.

3. **Testing the safety of vaccines**: Transgenic animals are also used to test the safety and efficacy of vaccines before they are administered to humans. This is an important step in vaccine development, making this option a benefit of transgenic animals.

4. **Producing useful biological products**: Transgenic animals can be engineered to produce proteins, hormones, or other biological products that can be beneficial for medical and pharmaceutical purposes. This is indeed a benefit of transgenic animals.

Based on this analysis, the option that is not a benefit of transgenic animals is **early detection of disease**.

### Step-by-Step Solution:
1. **Identify the benefits of transgenic animals**: Understand that transgenic animals are used for various research purposes, including studying treatments, testing vaccines, and producing biological products.

2. **Evaluate each option**: Analyze each provided option to see if it aligns with the benefits of transgenic animals.

3. **Determine the incorrect option**: Identify that early detection of disease is not a benefit of transgenic animals, as it relies on specific diagnostic techniques rather than the animals themselves.

4. **Conclude the answer**: State that the option regarding early detection of disease is the correct answer to the question.