Effect of earth shrinking on acceleration due to gravity

If the radius of the earth were to shrink by one percent, its mass remaining the same, the value of \(g\) on the earth’s surface would

increase by 0.5%

increase by 2%

decrease by 0.5%

decrease by 2%

Since \(g = \frac{GM}{R^2}\), differentiating gives \(\frac{dg}{g} = -2 \frac{dR}{R}\). A -1% change in R leads to a +2% change in g.