OPTIONS:
a). The advantages of 3-D printing;
b). The disadvantages of 3-D printing;
c). The changes brought by 3-D printing;
d). The rapid development of science;
Q: Read the following article and answer the question. Article: If your pen broke at school today,what would you do?You would go to a shop and buy a new one.What if you could simply print out a real,working pen with your 3-D printer without leaving your room? The 3-D printer has been used to make many different things.People have made cups cars and even an airplane with it. Doctors have been using 3-D printers for several years.People's nervous systems have been printed out in 3-D form medical research.Some body parts have been printed and used in hospital.Several months ago,doctors used a 3-D printer to rebuild Ten years ago people could only see 3-D printing in science fiction movies.But now 3-D printing is here and it's bringing big changes. Unlike normal printing that can only copy a 2-D picture with ink.3-D printing can build almost anything made from material.The printer layers the material in different shapes to create the object you want to be copied.the face of a person who had a bad accident.In the future,it is expected that the printer will make human organs to save more lives. However there are _ to the printer.At the moment,printing can be quite slow and it's still rather expensive.The average price of a household printer is around $1,700,not including the cost of the materials. But as the technology develops,it shouldn't be long before disadvantages are improved.Only time will tell where this new technology will take us. ,A, B, C, D,. Question: What's the best title of the passage? Answer:
A:
c).