Which of the following is part of the 6-by-6 rule?

i need !

universal windows platform is an open source api created by microsoft and first introduced in windows 10. the purpose of this platform is to develop universal apps that run on windows 10, windows 10 mobile, xbox one and hololens without the need to be re-written for each. it supports windows app development using c++, c#, vb.net, and xaml. the api is implemented in c++, and supported in c++, vb.net, c#, f# and javascript. designed as an extension to the windows runtime platform first introduced in windows server 2012 and windows 8, uwp allows developers to create apps that will potentially run on multiple types of devices.

answer; i believe the correct answer is 50 pounds;