Which method should they use?

A. Use Google App Engine with Google Cloud Endpoints. Focus on an API for dealers and partners

B. Use Google App Engine with a JAX-RS Jersey Java-based framework. Focus on an API for the public
C. Use Google App Engine with the Swagger (Open API Specification) framework. Focus on an API for the public
D. Use Google Container Engine with a Django Python container. Focus on an API for the public
E. Use Google Container Engine with a Tomcat container with the Swagger (Open API Specification) framework. Focus on an API for dealers and partners

Explanation:
Develop, deploy, protect and monitor your APIs with Google Cloud Endpoints. Using an Open API Specification or one of our API frameworks, Cloud Endpoints gives you the tools you need for every phase of API development.

From scenario:
Business Requirements
Decrease unplanned vehicle downtime to less than 1 week, without increasing the cost of carrying surplus inventory
Support the dealer network with more data on how their customers use their equipment to better position new products and services
Have the ability to partner with different companies – especially with seed and fertilizer suppliers in the fast-growing agricultural business – to create compelling joint offerings for their customers.

Reference: https://cloud.google.com/certification/guides/cloud-architect/casestudy-terramearth