Which one of the following is the correct sequence of the given substances in the decreasing order of their densities?

Density is mass per unit volume, so substances with larger density values are heavier for the same volume. Pure gold has a very high density, about 19.3 g·cm−3, making it the densest of the three materials listed. Mercury, a dense liquid, has a density around 13.5–13.6 g·cm−3, intermediate between gold and common structural steels. Typical carbon or alloy steels have densities near 7.8–8.0 g·cm−3, substantially lower than both gold and mercury. Therefore, arranging the three in decreasing order of density gives: Gold > Mercury > Steel, which corresponds to option 2.