With reference to the 'Classical Conditioning Theory of Learning', which of the following statements is most appropriate and correct regarding the scientific nature of the concepts 'Extinction', 'Spontaneous Recovery', and 'Stimulus Generalization' in Russian physiologist Ivan Pavlov's experiments and their interrelations in learning processes?

According to Ivan Pavlov's Classical Conditioning Theory, when a conditioned stimulus (CS) is repeatedly presented without the unconditioned stimulus (US), the conditioned response (CR) begins to weaken, which is called 'Extinction'.

Key Concepts:

• Extinction: Weakening of CR when CS is presented alone.
• Spontaneous Recovery: The reappearance of a weakened CR after a rest period, proving that learned pathways are not completely destroyed but only temporarily suppressed.

Therefore, option 'a' is completely true and scientifically accurate.