Read the excerpt from the introduction for "On Becoming an Inventor" by Dean Kamen. Invention is predominantly individualistic. Everything . . . comes from the lone worker who follows the fleeting inspiration of a moment and finally does something that has not been done before.

This quote is from the inventor of a three-phase motor, Nikola Tesla. It fits the description in every respect of Dean Kamen, the owner of more than one hundred patents.

As a young teenager in Rockville Center, New York, one of four children, whose father was a comic book artist and his mother a schoolteacher, Dean started tinkering with sound and light boxes in his bedroom, "which caused lights to go off and on, and deafening sound to come from his radio," said his mother.

Their indulgent parents allowed Dean and his older brother Barton to experiment, raising as many as one hundred live rats and to set up a workshop in their basement on Long Island. Dean stocked the basement laboratory with machinery to help create new audio/visual equipment. This led to his first patent and a sizable financial reward while still in high school.

Which line from the excerpt expresses fact rather than opinion?