Considering the situation described above, Arianna is required to file a Schedule B if her dividend income is higher than "<u>$1,500</u>."
According to the existing rules and regulations, individuals must file a Schedule B when the total amount of dividends or interest received is over <u>$1,500</u>.
Generally, it should be noted that Schedule B only requires individuals to report information about the received dividend and interest income.
Hence, in this case, it is concluded that the correct answer is "<u>$1,500</u>."
Learn more about Schedule B here: brainly.com/question/25116167