Were you a bird, you ___________________ in the sky.
in conditional sentences if your conditional sentence (if i ...) is in past perfect then in resultant sentence 'would have' will be used.
If i had extra clothes , i would have donated them.
When conditional sentences are imaginary sentences like if i were a cricketer.....then in resultant sentences we have to use 'would'.
The answer is definitely
A...... would fly
A is the answer. You can see the official GATE key here.