Having an app in a citrix environment with multiple text-boxes that look the same (size/style), how can you identify one of them to type into?

A. and D.

Explanation:

Based on the information provided within the question it can be said that you can only identify one of them to type into by clicking relative to an unique text/image next to the textbox, otherwise you would not be able to identify it if it does not have something unique next to it such as unique text or an image that differentiates it from the rest.