Which of the following is one of the four cornerstones of adult learning?

The correct answer highlights a fundamental principle of adult learning: the idea that adults learn best through hands-on experiences. This approach recognizes that practical engagement is crucial for retaining knowledge and mastering skills. When adults are actively involved in their learning process, they can apply concepts in real-world situations, which enhances understanding and retention.

This principle emphasizes the importance of experiential learning, where adults participate in activities that require them to practice new skills or solve problems directly related to their interests or jobs. By learning through doing, adults are more likely to connect the material to their own experiences, leading to deeper insights and meaningful applications of what they've learned.

The other choices do not align with established principles of adult learning. The concept of competition, preference for lectures, or learning in isolation fails to acknowledge the collaborative and practical aspects that are more effective for adults seeking to acquire new knowledge and skills.