Which of the Following Is an Example of Primary Innovation

Multiple Choice

Which of the following is an example of primary innovation?

A) the discovery that when clay is heated to a certain temperature it will become permanently hard
B) the discovery that meat cooked over an open flame might cause some cancers
C) the realization that meat when exposed to heat will become softer and easier to chew
D) the discovery of the principle of the wheel
E) all but b