Ancient Roman concrete has long interested engineers because many Roman structures have survived for millennia. For years, researchers assumed the material’s durability came from a rare volcanic ash used in its production. In 2023, however, a team of researchers found that small white mineral chunks embedded in the concrete could dissolve and recrystallize, filling cracks that formed over time. This discovery suggests that Roman concrete may have been self-repairing, and it has inspired engineers to experiment with similar self-healing materials for modern construction.
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Verbal·Craft and Structure·Text Structure and Purpose
mediumWhich choice best describes the overall structure of the text?
A
It describes a long-standing assumption, then presents new findings that challenge it.
B
It poses a question, then evaluates several proposed answers to it.
C
It recounts a historical event, then explains its lasting cultural influence.
D
It presents a problem, then describes two competing solutions and endorses one of them.