D Any mistake made in the printing of a s

题目：

D

Any mistake made in the printing of a stamp raises its value. A mistake on one inexpensive postage stamp has made the stamp worth a million and a half times its original (本来的) value. The mistake was made more than a hundred years ago in the British colony (殖民地)of Mauritius, a small island in the Indian Ocean. In 1847 an order for stamps was sent to a London printer—Mauritius was to become the fourth country in the world to issue (发行) stamps.
Before the order was delivered(传达), a party was planned at Mauritius’Government House, and stamps were needed to send out the invitations. A local printer was told to copy the design for the stamps. He printed the words " Post Office " instead of " Post Paid " by mistake on the several hundred stamps that he printed.
Today there are only twenty-six of these misprinted stamps left—fourteen Onepenny Orangereds and twelve Twopenny Blues. Because of the Twopenny Blue’s rareness (稀少) and age, collectors have paid as much as $ 16800 for it.

The mistakes on the locally printed postage stamps was in the ______.

A．size

B．words

C．price

D．colour