You recently developed a deep learning model. To test your new model, you trained it for a few epochs on a large dataset. You observe that the training and validation losses barely changed during the training run. You want to quickly debug your model. What should you do first?

A. Verify that your model can obtain a low loss on a small subset of the dataset B. Add handcrafted features to inject your domain knowledge into the model C. Use the Vertex AI hyperparameter tuning service to identify a better learning rate D. Use hardware accelerators and train your model for more epochs