Why is poster art effective as expression in a social movement?

It awakens collective feeling through simple symbols and a sharp message

The governing concept is visual communication used for collective expression. A poster combines a noticeable image, limited visual elements, readable lettering, symbols, and a concise slogan so that people can understand its message quickly, even from a distance. In a social movement, this clarity can express shared concerns, build solidarity, and encourage public participation. Therefore, option A is correct. Option B contradicts the public nature of posters, and option C denies their communicative purpose. Option D reduces poster art to colour practice and ignores its social message, composition, symbolism, and ability to reach many viewers. Effective design makes an idea memorable without requiring a long explanation.

This is a Class 9 Art Education question. Chapter: Introduction to Art. Topic: Art as a form of expression.