Utilize the input text as a context reference, choose the right relationship between 'Safaricom' and 'Nairobi' from the options.
Options: headquarters location, developer, location of formation, founded by

With over 12 million subscribers accessing the internet through its network, Safaricom pioneered its LTE Advanced (4G) proposition in December 2014, launching the most advanced version of the 4G system for mobile networks in Nairobi and Mombasa.
headquarters location