Select the incorrect statement $:-$

• A
  Animals that have had their $\text{DNA}$ manipulated to possess and express an extra (foreign) gene are known as transgenic animals.
• B
  Transgenic animals can not be specifically designed to allow the study of how genes are regulated.
• C
  Many transgenic animals are designed to increase our understanding of how genes contribute to the development of disease.
• D
  Transgenic mice are being developed for use in testing the safety of vaccines before they are used on humans.