Identify the information which points to a flaw in the argument below:

Thomas Edison made a vow, when he was a young child, that as an adult he would work with machines. Humanity should feel fortunate, because had Edison not made that vow, he would never have invented important machines such as the phonograph, movie projector, and lightbulb.

A
Other inventors of famous machines never made the same vow Edison made.
B
Thomas Edison may have invented things other than machines had he not made his vow.
C
Thomas Edison only invented machines that he dreamed up while still a child.
D
Thomas Edison may have become an inventor of machines even without making a vow as a child.
E
Edison's vow only referred to his working with machines, but not necessarily inventing them.