This theory, promoted by John Dewey, established the concept that education was key to the search for the truth about ideals and institutions.

The correct answer is B. Pragmatism.

Pragmatism is a philosophical approach that emphasizes the practical application of ideas by acting on them to test their validity. John Dewey was a key figure in this movement, advocating that education is a crucial means to explore and establish truths about society and its institutions. By engaging in practical experiences and reflective thinking, individuals can better understand and improve their ideals. If you have more questions or need further clarification, feel free to ask!