Which textual evidence best develops this viewpoint?

just because something has not yet been done doesn't meant it can't be done.

a. "people said that man could not fly, but in 1903, orville and wilbur wright made the first sustained powered flight in
a heavier-than-air machine."

b. "most importantly, this is your life, not someone else's, and it's your responsibility to live it."

c. "or would you rather spend the rest of your life wondering what might have happened if you had soldiered on? "

d. "but when you look back on your life, wouldn't you rather have succeeded or failed because of the choices you
made, not because of some rude thing someone said? "