Answer: The answer is (C) C and E.
Step-by-step explanation: We are given a figure including a plane 'w' and a number of points A, B, C, D, E and F around the plane. We are to select the pair of points from the given options that lie within the plane 'w'.
We can see in the figure that the points A and F lie above the plane 'w'; the points B and D lie below the plane 'w'; the points C and E lie on or within the plane 'w'.
Since we are to find the set of points lying within the plane 'w', so option (C) is the correct option.