Which of the following was an important invention in the 19th century

A．illustrate how wheels, cameras and computers were invented
B．discuss how great inventions influence our way of living
C．compare people's attitudes towards new inventions
D．compare inventions of the 19th century with that of the 20th century

A．In the early 1800's.
B．In the late 1800's.
C．In the second half of the 19th century.
D．In the first part of the 20th century.