You learned about the general concept of parallax, and the video offers a review of the basic ideas. To check your understanding of the concept, which of the following is a valid way of demonstrating parallax for yourself?a. Get a camera, and photograph a person who is running back and forth. b. Hold up your hand in front of your face, and move it slowly back and forth. c. Hold up your hand in front of your face, and alternately close your left and right eyes. d. Look up at a star, and notice how it moves toward the western horizon during the night.