Genetic engineering has been successful used for producing
a. Transgenic mice for testing safety of polio vaccine before use in humans
b. Transgenic cow-Rosie which produces high fat milk for making ghee
c. Animals like bulls for farm work as they have super power
d. All of the above

Hint: Genetic engineering is the technique by which genes of the organisms get directly manipulated using biotechnology. Genetic engineering uses recombinant DNA to change the phenotype of the organism. For example golden rice, carrots which help in the prevention of osteoporosis, purple tomatoes, bananas, etc.Genetic engineering has the potential to cure genetic disorders in humans by changing the defective gene with normal functional genes.

Complete answer:
Transgenic mice are produced for being used in the testing safety of vaccines before they are used on the body of human beings. Transgenic mice are used for testing the safety of the polio vaccine.

Transgenic cow-Rosie produced human protein enriched milk. This milk contains the human alpha lactalbumin. This is a more beneficial product for human babies as compared to natural cow milk.

Super power bulls are not produced by genetic engineering instead they are produced by animal breeding.

Hence, the correct answer is option (A).

Additional information:
Transgenic mice are the models which have their genes altered for the gene function study. These are used for the study of heart disease, diabetes, anxiety, obesity,arthritis, ageing, Parkinson's disease, Alzheimer's disease and different types of cancer.

Steps involved in genetic engineering are:
- DNA extraction
- Gene cloning
- Transformation
- Blackcross breeding

Genetic engineering can cause cross contamination, wildlife poisoning, weediness increase, or worse virus production.

Note: Genetic engineering also known as genetic manipulation or genetic modification, it is a technique which changes the genetic constitution of the cells to alter the phenotype of an organism. For example GMO ( Genetically modified organisms) such as transgenic mice, these are used for the test trial of vaccines before applying on the human body. Genetic engineering is used to fight diseases, forming new foods, curing young and prenatal child illness, providing disease resistance, fastens the plant and animal growth, increases age, etc.