The correct answer is A. experience.
Experience is the knowledge or skill that is gained by doing, seeing, or feeling something over a period of time. It is a valuable tool for planning and decision-making, as it can help us to learn from our past mistakes and successes. By consulting our experience, we can make more informed decisions about the future.
Option B, experiment, is a method of learning by trying something new and observing the results. It is a valuable tool for scientific research, but it is not as useful for planning and decision-making, as it does not take into account the past.
Option C, the model, is a representation of something that is real or imagined. It can be used to help us understand a complex system or to make predictions about the future. However, models are not always accurate, and they should not be used as the sole basis for planning and decision-making.
Option D, none of these, is not the correct answer.