Refer to figure. 
HUMAN EYE - INNER LAYER

The retina is a light-sensitive layer inside the eyeball where the photoreceptors are found. Images are focused on the retina where the photoreceptors convert them into nerve impulses that are then transferred the brain. The retina has two types of photoreceptors:

1. Rods: They are found in the periphery of retina and they enable scotopic (low-light) vision. The rods can only create black and white images and are also responsible for peripheral vision.

2. Cones: The fovea, at the retina's center, contains only cones that enable photopic (bright-light) vision. The cones are responsible for direct vision and require bright light to function. They are used to detect colours.

Rods → Night vision, Peripheral vision (black and white images) 
Cones → Day vision, Central vision (colourful images)

When we look at an object directly, it will be focused on the fovea area where only cones exist. The cones are responsible for day vision. For night vision, the rods should be used instead which are located at the periphery of the retina and not at its center (fovea). If looking slightly at the side of the objects, their side will be focused at the fovea and their central parts will be focused on the retina where rods exist. Therefore, looking at the side of an object at night provides the best night vision.

Let's analyze the given options:

Looking directly at the object to use the cones in the fovea. → INCORRECT. The cones are responsible for day vision. The rods should be used instead for night vision.

Rapidly blinking to refresh the rhodopsin in the retina. → INCORRECT. Rhodopsin is a light-sensitive pigment found in rod cells, and it is responsible for night vision. Blinking only helps to moisten and clean the surface of the eye, not to regenerate rhodopsin.

Looking at the side of the object in order to focus the object on the rods. → CORRECT. The eyes rely on rod cells for night vision, which are more sensitive to dim light. These rods are located around the edges of the retina, not in the center. By looking slightly to the side of an object, you allow the image to fall on these rod-rich areas, improving your ability to see it at night.

Increasing the brightness of the cockpit instrument lights. → INCORRECT. Increasing the brightness in the cockpit will make it harder to see objects outside the cockpit. This will reduces dark adaptation and worsen night vision.