Concept:Brainstorming is a creative group technique where ideas are generated freely without criticism, aiming to boost spontaneous thinking.Explanation:Brainstorming was proposed by Alex Osborn. It encourages participants to share any idea that comes to mind, without discussing its merits or demerits. This free flow of ideas helps students become more spontaneous and sensitive in their thinking. The four key rules are: no criticism, welcome wild ideas, focus on quantity, and combine or improve ideas. By removing judgment, students feel free to express themselves, improving their spontaneous sensitivity. This technique is not directly used for vocabulary, spelling, or sentence formation, but for generating creative ideas spontaneously.Answer:Option A: improving students' spontaneous sensitivity