13. Which of the following rocks is likely to provide the best reservoir for water/oil/gas: Sedimentary rocks of (old) Precambrian age; Sedimentary rocks of (young) Tertiary age; Metamorphic rocks of Precambrian age; Igneous rocks of Mesozoic age.

A. Sedimentary rocks of Precambrian age

Explanation:

As most of the sedimentary rocks contain mineral deposits like shale, quads, calcite. Amongst all major types of rocks sedimentary rock are commonly known for fossil deposits and fossil in the end consist of a thin layer of carbon the process is known as Carbonisation and is responsible for formation of fuels and coal etc.