The recommended approach for isolating environments like development (DEV), testing (QAS), and production (PROD) in SAP BTP is to use separate subaccounts for each. A subaccount is a structurally independent unit with its own applications, services, subscriptions, and user authorizations. This strict separation ensures that activities, configurations, or potential failures in one environment (e.g., a faulty deployment in DEV) do not impact the stability, security, or data of another environment, particularly the productive one.

A. Shared service keys: Sharing keys between environments would break isolation and create a significant security risk, directly contradicting the goal.

C. Single role collection: Using one role collection across different environments would lead to improper authorization management and violate the principle of least privilege.

D. Common destinations: Sharing destinations could cause a development application to inadvertently connect to a production backend system, compromising data integrity and stability.

1. SAP Help Portal, SAP Business Technology Platform, "Setting Up Your Account Model". This guide recommends a multi-subaccount strategy, stating, "We recommend that you create at least three subaccounts for your application: one for development, one for testing, and one for production."

2. SAP Help Portal, SAP Business Technology Platform, "Account Model". The documentation defines a subaccount as an independent entity, which is the basis for creating isolated environments for different development stages.