Read the passage below and answer the question that follows.
In 1756, the British engineer John Smeaton was commissioned to rebuild the Eddystone Lighthouse, which had been destroyed by fire. To ensure the new masonry tower could withstand the relentless battering of the sea, Smeaton sought a mortar that would cure under water. Through systematic experimentation, he discovered that lime burned from limestone containing a high proportion of clay set successfully even when submerged. This pioneering work led to the rediscovery of hydraulic lime, a material that had been lost since Roman times. Smeaton's innovative cement formulation not only secured the lighthouse's structural integrity for over a century but also laid the groundwork for modern Portland cement.
According to the passage, Smeaton's experiments revealed that mortar could harden underwater if it was made using which of the following?
- limestone that possessed a significant amount of clay.Answer
- Ba cement mixture originally created by Roman builders.
- Cclay that was heated independently before being combined with lime.
- Dmortar that had been dried thoroughly before being exposed to seawater.