The correct answer is option 3, which means all of the statements 1, 2, and 3 are true.

To understand why, let`s break it down:

Statement 1: (x^2 + u^2 = 1)

The given equation is (x^2 + y^2 = 1), which represents a circle with radius 1 centered at the origin in the xy-plane. If we substitute y with v (from the second equation), we get: (x^2 + v^2 = 1). Now, if we substitute u with -x (from the third equation), we get: (x^2 + (-x)^2 = 1). Simplifying this we get: (x^2 + x^2 = 1), which is true.

Statement 2: (y^2 + v^2 = 1)

Again, using the given equation (x^2 + y^2 = 1) and substituting x with u (from the second equation), we get: (u^2 + y^2 = 1). Now, if we substitute v with -y (from the third equation), we get: (u^2 + (-y)^2 = 1