Final answer:
The period characterized by division and conflict in ancient China, eventually unified under Shi Huangdi, is known as the Warring States Period (475–221 BCE).
Step-by-step explanation:
The historical period in China marked by division, frequent wars, and ending with the unification under Shi Huangdi is A) The Warring States Period.
This era, lasting from 475–221 BCE, was characterized by a fragmented political power structure following the decline of the Zhou dynasty. Intense warfare occurred as seven competing states vied for dominance.
The state of Qin ultimately conquered the others, with Shi Huangdi founding the first Chinese empire, thereby ending the tumultuous period. Philosophers and strategists like Confucius proposed various ideals to achieve societal harmony during this time, giving rise to the 'Hundred Schools of Thought.'