Over 95% of all existing transgenic animals are:

The correct answer is Option (1) → Mice

Transgenic animals carry and express a foreign gene put into their DNA. Rats, rabbits, pigs, sheep, cows and fish have all been made transgenic, but mice form by far the largest share.

NCERT Extract:
Transgenic Animals – “Animals that have had their DNA manipulated to possess and express an extra (foreign) gene are known as transgenic animals. Transgenic rats, rabbits, pigs, sheep, cows and fish have been produced, although over 95 per cent of all existing transgenic animals are mice.”