Correct Answer: D
Explanation:
Sol.
Diamond is metastable Allotrope of Carbon . Marble is a metamorphic rock composed mainly of crystalline calcium Carbonate or Calcium Magnesium Carbonate. The most common component of sand is Silicon dioxide in the form of quartz. Ruby is considered as one of the four precious stones together with Sapphire, Emerald and Diamond. In Chemistry, the ruby gemstone is a mixture of Aluminium, Oxygen and Chromium.