How do I open a hidden text box, when a particular option is checked?

[KevinBurkman]

I am working on a survey, which requires a hidden text box to open, when a particular option is checked ("DEP GeoHub") in the survey. 

I am having difficulty figuring out how to do this, and  I suspect that it involves the use of the relevant field. I was able to successfully do this with my "Other" option in the survey, but this is a stand-alone question; my issue seems to be an option within a option.

I have attached below screenshots for the survey, survey sheet and choices sheet below. Any suggestions would be greatly appreciated.

Thank you,

Kevin

Survey view

Survey sheet

Choices sheet

[ZacharySutherby]

Hello Kevin Burkman‌

You can add your text question and in the relevant box put something like selected(${question2c},'q2cdepgeohum'). 

I have attached a test XLSForm to take a look and test it out. 

Thank you, 

Zach