Spatial disorientation is a condition where a person is unable to correctly determine their position, movement, or orientation in space. It means your brain is confused about which way is up, down, or which direction you’re moving. It usually occurs when the sensory systems that help with orientation give misleading information, such as vision, inner ear or proprioceptive senses (seat-of-the-pants). When these systems conflict, your brain makes the wrong interpretation. Spatial disorientation happens when you trust your senses instead of reliable instruments or references, leading to incorrect perception of position or motion. The pilot may recover from spatial disorientation by trusting the cockpit instruments instead of their senses.

Let's examine the given options:

It should be treated by looking at and believing the aircraft flight instruments. → CORRECT. Instruments provide accurate, objective information. They are not affected by sensory illusions. This is the standard and safest response to spatial disorientation.

It will pass if the pilot closes their eyes for a few seconds. → INCORRECT. The aircraft still needs to be controlled. Closing the eyes during flight is not a safe option.

It can be overcome by trusting the "seat of the pants" sensations. → INCORRECT. This refers to body sensations that caused spatial disorientation. Trusting them will likely make the situation worse.

It requires the pilot to look at the ground to recalibrate the inner ear. → INCORRECT. A visible horizon can help reorient you. However, it may not be available (e.g., clouds, night, poor visibility) or we may confuse its orientation when over the sea (we may believe that the sea is the sky when already suffering from spatial disorientation). Instruments are still more reliable.