The question asks us to compare the values of A and B based on given equations; A = x^2 - y^2 and B = 20, with additional information that x + y = 10.

Option 1 and 2 suggest that A is greater than B or B is greater than A respectively. However, to confirm these, we would need to know the specific values of x and y.

Option 3 implies that A is equal to B, but again we cannot verify this without knowing x and y.

Option 4 states it is not possible to compare A and B due to inadequate data, which is correct. Although we have the equation x + y = 10, we don`t have enough information to determine individual values of x and y which are needed for calculating A. This equation has infinite solutions and we can`t determine a single value for A. Therefore, we cannot compare A and B definitively, making Option 4 the correct answer.