Correct option is A
The correct answer is (a) Only (A).
The Taj Mahal is primarily constructed from white marble, which is a metamorphic rock formed from the transformation of limestone under intense heat and pressure. The Red Fort, on the other hand, is mainly built from red sandstone, which is a sedimentary rock composed of sand grains cemented together. Therefore, only the Taj Mahal is an example of a monument built with metamorphic rocks.