What is the purpose of the HP Unified Functional Testing (UFT) Web Add-in Extensibility feature?

A.
It allows creation or improvement of support for third- party and custom web controls that are
not supported out-of-the box by the UFT web add-in.

B.
It provides a Web-based development environment to create new UFT Add-ins.

C.
It allows creation of customized Web 2.0 toolkits and controls.

D.
It provides an SDK and a set of APIs to extend support for GUI-less Web services.

Explanation:
And the Extensibility Accelerator is an integrated development environment (IDE) that
facilitates and accelerates the design, development, and deployment of support for third-party and
custom web controls that are not supported out-of-the-box.
http://www.skyitgroup.com/pub/files/SurvivalGuideforTestingModernApplications.pdf