A light ray passes from air (nā = 1.00) to three layers of the human eye: cornea (nā = 1.33), lens (nā = 1.41), and vitreous humor (nā = 1.33). The speeds of light in these mediums are, respectively, vā, vā, vā, vā. Which of the following must be true about the relationships between the speeds of light in the different media?