The correct answer is option 'D) Catastrophe theory'.

Catastrophe theory, as explained by the mathematician René Thom and expanded upon by the psychologist Albert Rajendra, suggests that a small change in any situation can result in a shift in behavior. This theory is based on the idea that sudden, unexpected shifts in behavior can occur due to a small change in the underlying conditions or parameters of a system. It emphasizes the nonlinear nature of human behavior and how it can be influenced by even minor changes in the environment or stimuli.

Catastrophe theory proposes that a system can exist in different stable states or equilibrium points, and a small change in the system's input can cause it to undergo a sudden and dramatic transformation from one stable state to another. This transformation is referred to as a "catastrophe" in the mathematical sense, where a small perturbation can lead to a large and discontinuous change in behavior.

The theory suggests that there are specific patterns or structures of behavior that underlie different situations. These patterns can be represented by mathematical models known as "catastrophe models." These models define the relationship between the input variables and the behavior of the system, allowing researchers to predict and understand the sudden shifts in behavior that can occur.

Catastrophe theory has been applied to various fields, including psychology, biology, economics, and physics. It has been used to explain a wide range of phenomena, such as sudden changes in animal behavior, decision-making processes, and social dynamics.

Overall, the catastrophe theory provides a framework for understanding how small changes in a situation can result in significant shifts in behavior. It highlights the nonlinear and unpredictable nature of human behavior, emphasizing the importance of considering the underlying structures and patterns that govern our actions.