Answer: I'm gonna say:
C. use of legalism
Explanation: https://www.history.com/news/han-dynasty-inventions
When a commoner named Liu Bang became the first emperor of the Han Dynasty in 206 B.C., it was the start of a period of more than 400 years that was marked by advances in everything from record-keeping to agriculture to health care.
“There were major inventions and developments in science and technology,” Robin D.S. Yates, the James McGill Professor in the Department of History and Classical Studies at McGill University in Montreal, explains. “As with all inventions, some of these only came into their own in later, sometimes much later times.”
Here are a few of the biggest breakthroughs of the Han Dynasty.
The Invention of Paper
Inventions of the Han Dynasty: Paper
The production of paper.
The earliest scrap of paper still in existence, a crude material made mostly from hemp fiber found in a tomb in China in 1957, dates back to sometime between 140 and 87 B.C. But Cai Lun, a eunuch in the Han court in 105 A.D., is credited as the inventor of the first really high-quality writing paper, which he fashioned by crushing and combining tree bark, hemp, linen rags, and scraps from fishing nets and then treating the mixture with lye to break it down into finer fibers, according to Li Shi’s book The History of Science and Technology in the Qin and Han Dynasty.
“Administrative documents continued to be written on boards of wood and slips of bamboo for several centuries—they preserved better, perhaps,” Yates explains. But after the collapse of the dynasty, Cai Lun’s improved paper came into its own.
The Suspension Bridge
Inventions of the Han Dynasty: Suspension Bridge
An undated photograph of a Chinese built suspension bridge, with boats docked at a pier in foreground, in the Szechwan Province, China.
According to Robert Temple’s highly-regarded history of Chinese inventions, The Genius of China, the Han Dynasty saw the development of the suspension bridge, a flat roadway suspended from cables, which probably evolved from simple rope bridges developed to span small gorges. But by 90 A.D., Han engineers were building more sophisticated structures with wooden planks.
Deep Drilling
Han Dynasty salt miners in the First Century B.C. were the first to build derricks and use cast iron drill bits to dig holes as deep as 4,800 feet into the Earth in search of brine, which they would extract from below with tubes, according to Temple’s book. The technique they developed was the forerunner of modern oil and gas exploration.
The Wheelbarrow
Inventions of the Han Dynasty: Wheelbarrow
A model of a Chinese wheelbarrow. It can accommodate a much larger wheel, thus reducing the rolling resistance, and by having the wheel almost directly under the load it reduced the weight on the user's arms.
The wheelbarrow was developed in China perhaps as early as 100 B.C, according to this 1994 article by M.J.T. Lewis in the journal Technology and Culture.
The Seismograph
Inventions from the Han Dynasty: Seismoscope
The Chinese astronomer, mathematician and seismologist, Zhang Heng (78-139 A.D.) described the earliest seismoscope known in about 132 A.D. Arriving shock waves displace a pendulum linked to a mechanism which opens the jaws of the dragon facing the direction of the earthquake. A ball falls from the dragon's teeth into the mouth of a toad below to record the event.
Zhang Heng, an early Chinese scientist, explored fields ranging from astronomy to clock-making. But he’s probably best known for creating the first device for detecting distant earthquakes, which he introduced to the Han court in 132 A.D. Its design was simple—an urn equipped with a pendulum.
When it picked up a vibration, it dropped a ball from the mouth of a metal dragon into a metal frog, creating a loud clang. The first time that happened, nobody in the court reportedly felt anything, but a few days later, a messenger from a village 400 miles away arrived to inform the emperor that an earthquake had occurred there.
The Blast Furnace
Right around the beginning of the Han Dynasty in the early 200s B.C., Chinese metallurgists built the first blast furnaces, which pumped a blast of air into a heated batch of iron ore to produce cast iron, according to Chinese technology historian Donald B. Wagner.
