A teacher is facing the problem of students’ poor spelling. She listed the probable causes for it and then decided to frame some steps to overcome it. This whole process is

The correct option is Action research.

Explanation:

Action Research is a reflective process of progressive problem-solving led by individuals working with others in teams or as part of a "community of practice" to improve the way they address issues and solve problems. In an educational context, it refers to a method used by teachers and educators to identify specific classroom problems (such as students' poor spelling), analyze their causes, and implement targeted action plans or strategies to overcome them.

Why other options are incorrect:

• Problem solving: While identifying a problem and finding a solution involves problem-solving skills, the structured, systematic cycle of diagnosing a classroom issue, planning interventions, and acting upon them in an educational setting specifically defines Action research.
• Improving spelling: Improving spelling is simply the desired outcome or objective of the teacher's effort, not the overall scientific/educational process being described.
• Applied research: Applied research aims to solve broader, practical problems of the modern world and test theoretical concepts on a larger scale, whereas action research focuses directly on a practitioner's immediate classroom environment and practice.