In the context of the organic evolution, the loss of limbs of snakes is explained by the phenomenon of

The correct answer is Option 1: use and disuse of organs.

This explanation is rooted in Lamarckism, a theory of evolution proposed by Jean-Baptiste Lamarck. According to this principle:

• Use and Disuse: Organs that are used frequently become more developed, while those not used undergo gradual reduction or disappear over generations.
• Snake Evolution: Ancestral snakes possessed limbs. However, to facilitate movement through narrow crevices and dense vegetation, they stopped using their limbs and relied on body undulations.
• Result: Continuous disuse led to the gradual vestigiality and eventual loss of limbs.

While adaptation to burrows (Option 2) provided the ecological pressure, the biological phenomenon explaining the physical loss in this specific context is the principle of disuse. Natural selection (Option 3) is a Darwinian concept, and inheritance of acquired characters (Option 4) is the subsequent step of Lamarck’s theory, but the loss itself is initiated by disuse.