You Are Building a Mobile App for Consumers to Post

Multiple Choice

You are building a mobile app for consumers to post cat pictures online. You will be storing the images in AWS S3. You want to run the system very cheaply and simply. Which one of these options allows you to build a photo sharing application without needing to worry about scaling expensive uploads processes, authentication/authorization and so forth?

A) Build the application out using AWS Cognito and web identity federation to allow users to log in using Facebook or Google Accounts. Once they are logged in, the secret token passed to that user is used to directly access resources on AWS, like AWS S3.
B) Use JWT or SAML compliant systems to build authorization policies. Users log in with a username and password, and are given a token they can use indefinitely to make calls against the photo infrastructure.
C) Use AWS API Gateway with a constantly rotating API Key to allow access from the client-side. Construct a custom build of the SDK and include S3 access in it.
D) Create an AWS oAuth Service Domain ad grant public signup and access to the domain. During setup, add at least one major social media site as a trusted Identity Provider for users.