As you most certainly know, there are two dominant types of smartphones. There are phones whose operating system is iOS (i.e., iPhones, all of which are made my one company, Apple) and there are phones whose operating system is Android. Android phones are made by many different companies, and we are going to assume a competitive market for Android phones. Furthermore, the value a consumer gets from a particular smartphone depends on the apps available for the smartphone.

Indicate which of the following could, by itself, could explain a shift out (and up) of the Android-phone demand curve from 2018 to 2019? To receive full marks, you must check all factors which would lead to an increase in demand, and no factor which would not lead to an increase in demand.

An increase in iPhone prices.
A decrease in consumer incomes if the Android is, on average, a normal good.
A popular app, Instagram, starts charging consumers in order to use the app.
Consumers expect higher quality Android phones in early 2020.
A decrease in the quality of Android phones.
An increase in iPhone quality.
An increase in consumer incomes if the Android is, on average, an inferior good.
A decrease in the price of an Adroid phone.