Correct Option
The correct option is Tripura Hills
Explanation
The Peninsul is the oldest and most stable landmass of India, primarily composed of ancient gneisses and granites. Its geological extent is not limited to the visible triangular plateau but includes underlying structures in the west and detached extensions in the northeast.
Analysis of Options
- Karbi Anglong and Meghalaya Plateau: These are extensions of the Peninsular Block in the northeast. They were originally part of the main Peninsular mass but were separated from the Chotanagpur Plateau by the Malda Fault (or Malda Gap) due to tectonic movements.
- Rajasthan Desert: While physiographically a desert, the underlying geological structure of this region is an extension of the Peninsular Block. The ancient crystalline rocks of the peninsula extend into Rajasthan, although they are largely covered by sand and sedimentary deposits.
- Tripura Hills: These are part of the Purvanchal range (Eastern Hills), which is a southward extension of the Himalayan mountain system. Geologically, they are young fold mountains formed during the Tertiary period and are composed of sedimentary rocks. They are not part of the ancient, stable Peninsular Block.
Key Takeaway: The Peninsular Block includes the Meghalaya Plateau and Karbi Anglong (separated by the Malda Gap) and the rock structure beneath the Rajasthan Desert. The Tripura Hills belong to the young fold mountain system of the Himalayas.