What major public works did the Sui dynasty undertake to unify China?

• A. The Grand Canal linking the Yangtze and Yellow Rivers to facilitate grain transport and centralized administration, and expansion of the Great Wall.
• B. The construction of the Grand Canal only.
• C. Expansion of the Great Wall only.
• D. The Southern Silk Road initiative.

Answer: (A)

The question tests how the Sui used big public works to knit the realm together through both transport/economy and defense. The Grand Canal, begun in this era, linked the Yangtze and Yellow River basins so grain and other goods could move efficiently to northern capitals. This boosted centralized administration because food, taxes, and manpower could flow where the central government needed them, keeping distant regions connected and responsive to imperial authority. At the same time, the expansion and reinforcement of the Great Wall helped secure frontiers, project power outward, and reduce border threats that could fracture control. Together, these projects show how the Sui aimed to unify China by creating a transportation network that integrated the economy with the state and by strengthening defenses to maintain a unified polity.

The other options miss part of the picture: a canal project alone would miss the border defense that the wall expansion provided; focusing only on border walls ignores the critical economic integration the canal enabled; and the Southern Silk Road was not a central public-work effort intended to unify the empire in the same way.