Which sentence best describes the difference between hyperpigmentation and hypopigmentation? Select the correct response: a. Hyperpigmentation is an overproduction of pigment, whereas hypopigmentation is a lack of pigment. b. Hyperpigmentation causes albinism, whereas hypopigmentation causes freckles. c. Hyperpigmentation is a lack of pigment, whereas hypopigmentation is an overproduction of pigment. d. Hyperpigmentation causes vitiligo, whereas hypopigmentation causes melasma.