Answer:
The answer is 2 (Two).
Step-by-step explanation:
The Qin dynasty's most famous ruler was the emperor Qin Shi Huang who unified China in 221 B.C after defeating the warring states.
The other ruler of this dynasty was Qin Er Shi, the son of Qin Shi Huang. During his reign, a mass civil unrest and economic decline finally destroyed the Qin dynasty.
Other well-known achievements of Qin dynaty were the building the Great Wall and a large army of Terracotta Warriors.