The following is a student draft of a report. It may contain errors.
Three-D Printing
(1) Three-D printing is one of the latest technological developments in the field of printing that helps to create three-dimensional objects using a variety of materials. (2) Three-dimensional objects have height, width, and depth. (3) Plastic, rubber, clay, metals, concrete, and ceramics are some of the materials that can be used to print a Three-D object. (4) To understand this, imagine a printer that can make a three-dimensional plastic rabbit toy instead of printing a rabbit on a piece of paper with ink.
(5) This technology is easy to use, as it is a printing machine that is connected to a computer. (6) The information of what is desired of the printer needs to be fed into the computer first, keeping in mind the final product. (7) Then, the printer starts building the object, starting from the base by adding a layer at a time. (8) As layer after layer gets added to the object, the object starts to take shape. (9) What is created is a three-dimensional physical object.
(10) Three-D printing can help people in various ways. (11) People have used it to create a small object like a mug to a much larger structure like an entire house. (12) The science of Three-D printing is rapidly developing and is playing an important part in the field of medicine. (13) Scientists and doctors have been able to make living tissue using Three-D bioprinting. (14) This technology has already been able to successfully create skin, bone, and heart tissue. (15) Three-D printing continues to pave the way for a bright future for mankind.
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Which transitional word or phrase should be added to the beginning of sentence 9?
A.
At the same time,
B.
Additionally,
C.
However,
D.
In the end,