She has no idea of what the book is about. She ____ have read it carefully.

A．Seeing
B．To be seen
C．Seen
D．Having seen

A．Many countries are trying to reduce the cost of making coins.
B．These days a penny made is a penny wasted.
C．There is disagreement over whether the U.S. should stop using pennies.
D．Many countries have stopped using pennies.