As a junior Data Scientist at a retail company, you are tasked with developing a deep neural network model using TensorFlow to enhance customer satisfaction for after-sales services. Your model's performance is suboptimal due to challenges in selecting appropriate learning rates, the number of hidden layers, and nodes, which are crucial for achieving fast convergence without overfitting. The project has tight constraints on computational resources and requires the model to be deployed in a cost-effective manner. In the context of machine learning, what is this optimization challenge known as? Choose the BEST option.