“I felt a huge relief…. in the possibilities of my body.” In the given context, the highlighted words refer to
(i) Shifting in the wheelchair, turning the wrist.
(ii) Standing up, walking.
(iii) speaking, writing.
(i) Shifting in the wheelchair, turning the wrist.
Compared to Hawking, the author was able to do much more even though confined to a wheelchair. Hawking couldn’t even move his wrists like the Author could.