Finger dexterity measures how capable a person is to handle or manipulate objects with hands. There are several ways to improve finger dexterity but none of the above is correct.
Option 1) exercise at the gym is incorrect since you can exercise your fingers at home with simple things such as grabbing a squeeze ball.
Option 2) is also incorrect as typing commonly used words is not a way to improve finger dexterity
Option 3) is also incorrect since even though it is recommended to heat your hands, it not recommended before typing but before exercising.
So the correct option is 4) none of the above.