Read this excerpt from a passage. Robots have been around longer than many people realize. Archytas, who lived in Greece over 2,300 years ago, is believed to have created the first robot. Archytas built a steam-powered mechanical bird that was able to flap its wings and fly over 200 yards. However, it was not until the late 1700s, with the beginning of the Industrial Revolution, that the world saw the large-scale use of more complex machines. Mechanization took another leap during the 1930s, when machines were introduced into many workplaces in order to increase productivity. Instead of hiring workers to perform tasks on an assembly line, factory owners used automated machines that could do the work of several people.

Then, in 1954, George Devol created the Unimate, a robotic arm. The Unimate began working on the assembly line at General Motors in 1961, taking on unpleasant, dangerous, and repetitive tasks. This robotic worker had many advantages over human workers. The Unimate did not require a salary, followed company rules, and never called in sick (although it did require the occasional repair). In addition, the Unimate could work twenty-four hours a day, seven days a week. Manufacturers that used the Unimate and other industrial robots saw a marked increase in productivity and a decrease in labor costs.

What features show this is an example of historical writing?

a.
It uses primary research that is based on the scientific method.

b.
It explains, outlines, and analyzes current trends.

c.
It focuses on the causes and consequences of certain events.

d.
It relies on anecdotes, examples, and testimonies as evidence.