The correct option is A Mice
95% of transgenic animals produced are mice.
Their genome has been fully sequenced and they are being extensively studied.
They are genetically more similar to humans. Hence, they are often used to study human genes. They can be genetically manipulated in various ways. Transgenic mice are being used to test the safety of the polio vaccine. They are being used for studying human diseases.
Advantages of mice include their small size, ease of maintenance, short reproductive cycle and production of a huge number of offspring. They are also suitable for in vitro fertilisation and culture of the embryos.