What implementation should an Architect recommend to UC?

Universal Containers (UC) has an existing web application that it would like to access from Salesforce without requiring users to re-authenticate. The web application is owned UC and the UC team that is responsible for it is willing to add new javascript code and/or libraries to the application .

What implementation should an Architect recommend to UC?
A . Create a Canvas app and use Signed Requests to authenticate the users.
B. Rewrite the web application as a set of Visualforce pages and Apex code.
C. Configure the web application as an item in the Salesforce App Launcher.
D. Add the web application as a ConnectedApp using OAuth User-Agent flow.

Answer: A