First stage of creative thinking is known as :

Psychologists model creative thinking as unfolding through a fixed sequence of mental stages. The classic four-stage model, proposed by Graham Wallas, names these stages in order: Preparation, Incubation, Illumination, and Verification — each stage marking a distinct kind of mental activity as a problem moves from being first encountered to being fully resolved.

1. Preparation — the thinker consciously defines the problem, gathers relevant facts, and reviews existing knowledge or prior attempts related to it. This is the opening stage of the sequence, matching the option asked for in the question.

2. Incubation — the problem is set aside from active attention and processed subconsciously, allowing the mind to form new associations in the background.

3. Illumination — an insight or solution suddenly and often unexpectedly enters conscious awareness.

4. Revision (verification) — the generated idea is consciously tested, refined, and validated against practical or logical criteria before it is finalized.

Because each of the later three stages presupposes that a problem has already been consciously defined and explored, the deliberate groundwork described in Preparation must come first, confirming it as the correct answer.