Statement 1 is Correct: During the Early Tertiary period, the western flank of the Peninsular block underwent tectonic subsidence (sinking). This led to its partial submergence beneath the sea, which formed the current submerged western coastline and disturbed the original symmetrical river pattern.

Statement 2 is Correct: The Peninsular Block is an ancient, rigid, and stable landmass. It primarily consists of highly denuded relict and residual mountains (remnants of older mountains). Standard geographical texts explicitly list the Aravali, Nallamala, Javadi, Veliconda, Palkonda, and Mahendragiri hills as key examples of these residual ranges.

Statement 3 is Incorrect: Because the Peninsular drainage system is much older than the Himalayan one, its rivers have reached maturity. They are characterized by broad, shallow, graded valleys with low gradients, rather than deep cuts. Deep gorges, V-shaped valleys, rapids, and waterfalls are indicative of youthful topography and active vertical erosion. These features are characteristic of the fast-flowing Himalayan river system, which cuts through young, weak, and flexible geological structures, unlike the stable Peninsular Block.

Therefore, option B is the correct answer.