The correct option is C A, B, C and D
Transgenic animals are those which have their DNA manipulated to express the foreign gene of interest.
Many transgenic animals are being developed to help us understand how genes contribute to the development of diseases. The purpose of these transgenic animals is to serve as models for human diseases so that investigation of new treatments for those diseases is possible.
Further, the dosage determination and efficiencies of the drugs can be tested on those model organisms before commercial utilisation. Today, transgenic models exist for many human diseases such as cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer's disease.
Hence, the correct option is d.