Which of the following are methods of learning?

All the listed items are methods of learning, so the answer is all of the above.

Trial and error is learning by attempts, refined into Thorndike's connectionism.

Imitation is learning by copying a model, central to Bandura's social learning.

Experimentation is learning by actively testing, fitting inquiry and constructivist views.

Questioning and reflection are higher methods that build understanding and metacognition.

Teaching too is a method of learning, since explaining to others deepens one's own grasp.