The correct answer is 5%, although it is not explicitly provided as an option in the question.

Let`s understand why the answer is 5%.

The acceleration due to gravity (g) is dependent on the mass of the Earth and the distance from the center of the Earth (radius). According to the formula g = GM/r^2, where G is the gravitational constant, M is the mass of the Earth, and r is the radius of the Earth.

If the radius of the Earth were to decrease by 1%, the new radius (let`s call it r`) would be equal to 0.99r (because a 1% decrease means a 0.01 decrease).

Substituting this new radius into the formula for g, we get g` = GM/(0.99r)^2 = g/0.99^2.

Now, let`s calculate the percentage decrease in g:

Percentage decrease = (g - g`)/g * 100

Substituting the values, we get (g - g`)/g * 100 = (g - g/0.99^2)/g * 100 = (1 - 1/0.99^2) * 100 =