The image of a light bulb is universally recognized as a symbol of an idea, creativity, or enlightenment.
This association originates from the popular depiction of light bulbs being "turned on" to signify a sudden realization or the birth of a new concept.
The light bulb symbolizes not just the moment of intellectual clarity, but also the broader notion of innovation and discovery.
In various cultural contexts, it is often used to represent problem-solving, inspiration, and intellectual breakthroughs.
Given these associations, option (D), which features the light bulb image, is the most appropriate choice.
The visual conveys a strong message of creativity and insight, aligning perfectly with the concept of generating or sharing an idea.
This symbolic image stands out as a clear and effective representation of mental illumination, making it the ideal choice in situations where the focus is on brainstorming, creative thinking, or the realization of new concepts.