For each function f(x, y,z) , determine whether its gradient points radially outward from the origin, radially inward toward the origin, radially outward from the z-axis, or radially inward toward the z-axis.

1. f(x, y,z) = x^2 + y^2

a. Points radially outward from the origin b. Points radially inward toward the origin c. Points radially outward from the z-axis d. Points radially inward toward the z-axis

2. \displaystyle f(x, y,z) = \frac{1}{x^2 + y^2 + z^2}

a. Points radially outward from the origin b. Points radially inward toward the origin c. Points radially outward from the z-axis d. Points radially inward toward the z-axis

3. \displaystyle f(x, y,z) = \frac{1}{x^2 + y^2}

a. Points radially outward from the origin b. Points radially inward toward the origin c. Points radially outward from the z-axis d. Points radially inward toward the z-axis

4. f(x, y,z) = x^2 + y^2 + z^2

a. Points radially outward from the origin b. Points radially inward toward the origin c. Points radially outward from the z-axis d. Points radially inward toward the z-axis