Reference:
Because you can use your own private VPN to access the Canada-only bucket from anywhere in the world.

Creating a machine learning (ML) model to analyze the demographics and behaviors of customers who have previously closed their accounts is an effective approach to identify at-risk customers. This model can predict which current customers are most likely to leave, allowing the organization to proactively offer discounts or improved services to retain them.
Option D: Create a ML model based on the demographics and activities of previous customers that exited is correct because it uses data-driven insights and AI to identify patterns and predict future customer behavior.
References:
* Google Cloud AI Platform: Building Machine Learning Models
* Google Cloud Customer Retention Solutions: Using AI and Machine Learning

Compute Engine lets you purchase committed use contracts in return for deeply discounted prices for VM usage. These discounts are referred to as committed use discounts. Committed use discounts are ideal for workloads with predictable resource needs. When you purchase a committed use contract, you purchase Compute Engine resources-such as vCPUs, memory, GPUs, local SSDs, and sole-tenant nodes-at a discounted price in return for committing to paying for those resources for 1 year or 3 years. The discount is up to 57% for most resources like machine types or GPUs. The discount is up to 70% for memory-optimized machine types.

Firebase/Firestore is easy to build and is suitable for user information that could bvary in nature.