In the context of the input sentence, determine the relationship between 'Apple Inc' and 'iPhone'.
Options: industry, director/manager, product/material produced, position held

BENGALURU/SAN FRANCISCO (Reuters) - Apple Inc (AAPL.O) shares slumped nearly 7 percent in after-hours trading as its fourth-quarter revenue forecast fell short of estimates and it missed some targets for iPhone sales.
product/material produced