Oxford English dictionary gives both pronunciations, your teacher is just a dick https://www.oed.com/dictionary/data_n?tab=factsheet#219838686 - it's like my ex who always gave me a hard time for saying "ant" instead of "ahnt."
Oxford English dictionary gives both pronunciations, your teacher is just a dick https://www.oed.com/dictionary/data_n?tab=factsheet#219838686 - it's like my ex who always gave me a hard time for saying "ant" instead of "ahnt."