Q. Off the chain means :

Dog without a leash
Broken machinery
Extremely good , wild or unrestricted
Out of prison
✅ The correct answer is c. Extremely good , wild or unrestricted.

Q. Inflate a cow is :

To exaggerate or below something out of proportion
To feed a cow too much
Not a valid idiom
A farming technique
✅ The correct answer is c. Not a valid idiom.