Question: Which of the following represents a family of circles with varying radii?

Options:

1. (x - h)^2 + (y - k)^2 = r^2
2. (x - h)^2 + (y - k) = r
3. x^2 + y^2 = r
4. x^2 + y^2 = kx

Correct Answer: (x - h)^2 + (y - k)^2 = r^2

Solution:

The equation (x - h)^2 + (y - k)^2 = r^2 represents a circle centered at (h, k) with radius r.