How does mudstone turn into metamorphic rock?

A. After a short period of time, particles of rock dissolve and harden again.

B. After many years, groundwater discolors and changes the rock.

C. Over a long period of time, temperature and pressure build up and change the rock.

D. Over time, layers form and spread out over a wide area to form rock.

Option (C)

Explanation:

Sedimentary rocks are formed due to the compaction and lithification sediments. For example, mudstone, sandstone, and shale.

Metamorphic rocks are those rocks that are formed when a sedimentary/igneous/other metamorphic rocks undergo changes in the pressure and the temperature conditions. Temperature and pressure are the main factors here. For example, slate, phyllite, schist, and gneiss.

Mudstone is a sedimentary rock that can convert into a fine-grained and foliated metamorphic rock called slate due to the increase in the temperature and pressure.

Hence, the correct answer is option (C).

C is the answer.

Metamorphic rocks is when a rock changes under time and lots of pressure.

Sedimentary is rocks made of sediment.

Igneous rocks are rocks that are made of magma.

Knowing this, C is closest to the definition of metamorphic rocks.