You are testing an application that will allow users to scan the bar code from a package mailing label and then receive

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You are testing an application that will allow users to scan the bar code from a package mailing label and then receive emails from the package shipper as the package moves through the various stages of its delivery (e.g., pickup, receipt at central processing, routing, delivery). If requested, the user can also receive a picture of the signature of the recipient of the package.
This is the second version of this application. The first version was web browser-based and was quite slow to start up. The new version is a native application with all the same functionality. It is expected that this application will have wide usage across a large set of networks with varying speeds and reliability.
Given this information, what would be the best approach for doing your testing to ensure the capabilities of the product are tested as well as the range of devices, environments and networks?

A. Use a remote device lab that is provided by a device manufacturer to ensure your application works across the whole family of devices.
B. Use crowd sourcing to get the widest distribution of device locations and types with minimal cost.
C. Use a set of simulators that can simulate the various capabilities of a wide variety of devices.
D. Use a cloud-based virtual test environment to simulate various devices and networks.