500
Which statement from the passage best explains Jan's contribution to all of us
a) "If people were lucky enough to own a pair of shoes, they wore them until the shoes literally fell apart"
b) "Usually one assembly ling could produce only fifty pairs of shoes a day, mainly because the lasting took so long, and few people knew the secret of how to do it"
c) "When the men in the patent office read through the design, they found the drawings and calculations so difficult that they had to travel to Massachusetts to have Jan explain his document"
d) "His machine had revolutionized the entire shoe industry in the United States and around the world"
What is d) "His machine had revolutionized the entire shoe industry in the United States and around the world"