Final answer:
Under high Gs the order of events typically starts with an increase in G-forces leading to tunnel vision followed by a gray out. Foveal vision demonstrates that when focusing on a point peripheral clarity decreases.
Step-by-step explanation:
The order of events a person might experience when exposed to high gravitational forces (high Gs) are as follows: Initially, as Gs increase there is a potential for tunnel vision due to the reduction of blood supply to the eyes and, by extension, the brain. This reduced blood supply can lead to loss of peripheral vision. If the conditions persist or worsen, the next stage can be a gray out, characterized by a dimming of vision which might progress to a complete loss of vision temporarily, known as a blackout, if G-forces continue to escalate.
The correct sequence according to the options provided is (a) Increased Gs, tunnel vision, gray out. To demonstrate the sensitivity of foveal vision one might look directly at a focused point, such as the letter 'G' in a word like 'ROGERS'. While focusing on 'G', the letters to the side may appear less clear due to the decreasing number of photoreceptor cells as you move away from the central fovea, which is responsible for sharp central vision.