Tenedor trucks, a forklift truck manufacturing company, trained its production unit on the new vacuum operated system which was replacing the hydraulic technology. The technicians had to let go of the old technology, and had to start from scratch as the new technology needed an entirely different approach. Which of the following best describes the technicians' experience? a. Overhauling b. Refreezing c. Masking d. Unfreezing e. Unlearning