The Development Stack is a collection of tools, languages, frameworks, build processes, APIs and so on that are used together for developing a digital product. 

So the tools I will choose for my mobile app is as follows:

Language: JavaScript

Reason: I reckon it would be easy, cheap and time saving as it is a scripting language.

Framework: Angular

Reason: Angular is an open source framework and is built by the infamous Google, which would mean that it would be easy for me to find solutions if I’m stuck easily.

Build processes: Webpack

Reason : It will bundle my code and remove unused parts, making my app consume lesser memory and hopefully making it faster.

API: Facebook Api

Reason: It’ll help me with the signup and log in process extremely easily.