The ability to see clearly at night is known as?

Answer: A — Night vision

Night vision refers to the ability to see clearly in low light or darkness. While dark adaptation (choice B) is a necessary process for achieving night vision, it specifically refers to the adjustment of the eyes to dim or dark environments. Photopic vision (choice C) is the ability to perceive and distinguish colors in good lighting conditions, while scotopic vision (choice D) is the ability to see in low light, such as during dusk or at night. Therefore, although these other options all relate to vision, they do not specifically refer to the ability to see clearly at night, making them incorrect answers.