The paragraph is followed by an incomplete phrase or sentence which summarizes the main idea of the paragraph. Choose the missing words of the phrase or sentence.

In the past, making structures quake-resistant meant firm yet flexible materials, such as steel and wood that bend without breaking. Later, people tried to lift a building off its foundation, and insert rubber and steel between the building and its foundation to reduce the impact of ground vibrations. The most recent designs give buildings brains as well as concrete and steel supports. These are called smart buildings.
Different ways to （） quake-resistance of a building.