Introduction:
Transgenic animals are genetically modified organisms that have been manipulated to contain foreign genes from other species. This technology has several applications, including the investigation of new treatments for diseases, testing the safety of vaccines, and the production of useful biological products. However, one of the listed benefits is not associated with transgenic animals.

Explanation:
Investigation of new treatments for diseases:
Transgenic animals provide a valuable tool for studying the mechanisms of diseases and developing new treatments. By introducing specific genes associated with human diseases into animals, researchers can observe the effects and study the underlying molecular pathways. This enables the development of targeted therapies and potential cures for various diseases.

Early detection of diseases:
Transgenic animals can be engineered to express specific genes that are linked to certain diseases, making them useful for early detection and diagnosis. By monitoring the expression of these genes, researchers can identify the presence of diseases at early stages, allowing for timely medical intervention and treatment.

Testing the safety of vaccines:
Transgenic animals play a crucial role in vaccine development and safety testing. They can be engineered to express human immune system components, enabling the evaluation of vaccine efficacy and safety before human trials. These animals provide valuable insights into the immune response and potential adverse effects of vaccines, ensuring their safety and effectiveness.

To produce useful biological products:
Transgenic animals can be used to produce valuable biological products, such as therapeutic proteins and antibodies. By introducing genes encoding these products into animals, they can serve as living bioreactors, producing large quantities of specific proteins or antibodies that are difficult to obtain through traditional methods. This has significant implications for medical treatments and research.

Conclusion:
Based on the given options, the benefit of transgenic animals that is not listed is the early detection of diseases (option B). Although transgenic animals can be used for disease modeling and understanding the molecular mechanisms, their direct application for early disease detection is not a commonly recognized benefit. Other techniques and diagnostic methods are typically employed for early disease detection in humans.