Please help me answer

Question 16 Solve the problem. Let f(x,y) = In (x 2 + y 2). Which one of the following curves is a simple closed path in the domain of the function f? The rectangle with vertices at (-3, 2), (3, 2), (3, -2), and (-3, -2) The unit circle x2 + y2 = 1 The ellipse + : 1 The unit circle (x - 5)2 + y2 = 1