Utilize the input text as a context reference, choose the right relationship between 'Starbucks' and 'coffee' from the options.
Options: currency, chairperson, product/material produced, chief executive officer

Yet on July 6, Starbucks said that its costs were rising and that it was raising the price of much of its brewed coffee by 5¢ to 20¢ a cup.
product/material produced