Step 1: Understanding the Concept:
The question requires identifying the defining characteristic of the Naturalism literary movement.
Step 2: Detailed Explanation:
\[\begin{array}{rl} \bullet & \text{Naturalism arose in the late 19th century, stemming from Realism. While both aim to portray life authentically, Naturalism is not merely Realism. } \\ \bullet & \text{Determinism is central to Naturalism. It suggests that uncontrollable factors like heredity, social environment, and basic instincts dictate characters' lives and destinies. } \\ \bullet & \text{Thus, Naturalism depicts life shaped by these unavoidable forces. It commonly portrays lower-class characters struggling to survive in a challenging world. } \\ \bullet & \text{Options (B) and (C) incorrectly associate Naturalism with an interest in nature, which is more typical of Romanticism. } \\ \end{array}\]
Step 3: Final Answer:
Option (D) provides the most precise definition.