The correct option is (a).
Explanation
Fold mountains are formed due to the collision of tectonic plates, leading to the folding of the Earth's crust. They are classified into Young Fold Mountains and Old Fold Mountains based on their geological age. This classification determines their physical characteristics, such as height, slope, and the sharpness of their peaks.
Statement-wise Analysis
- Statement 1 is Correct: The Himalayas (Asia) and the Alps (Europe) are classic examples of Young Fold Mountains. They were formed during the Tertiary period (relatively recent in geological terms). Because they are young, they have not yet been significantly worn down by erosion. Consequently, they are characterized by high elevations, rugged relief, and sharp, high conical peaks.
- Statement 2 is Incorrect: The Aravali range in India is one of the oldest fold mountain systems in the world. Unlike young fold mountains, the Aravalis have been subjected to denudation and erosion for millions of years. They are now classified as Relict or Residual Mountains and are not currently rising in the same manner as active young fold belts like the Himalayas.
- Statement 3 is Incorrect: The Appalachians in North America are Old Fold Mountains formed during the Paleozoic era. Due to prolonged exposure to erosional forces over vast geological timescales, their original sharp features have been worn down. Therefore, they are characterized by rounded peaks and relatively low elevations, rather than high conical peaks.
Key Takeaway
Young Fold Mountains (e.g., Himalayas, Alps, Andes) feature high, sharp, conical peaks and rugged relief due to recent formation. Old Fold Mountains (e.g., Aravalis, Appalachians, Urals) feature lower elevations and rounded peaks due to extensive erosion over geological time.