BONUS: Mike Sievert mentions that T$-$Mopile's strategy involves making substantial investments in customers. What does adding travel perks amount to and is it a sustainable advantage?

$$ It is a way to reduce supplier power and it is sustainable because foreign networks do not have negotiating power against T$-$Mobile.

It is an increase in rivalry which is a cost for all competitors but its sustainable because it cannot be copied.

It is a way to reduce the threat of new entrants and it is sustainable because there are few potential new entrants in the market.

It is an increase in rivalry which is a cost for all competitors but it's not sustainable because all the main competitors he mentions can easily offer the same. $q,$ ear my selection