The $80/20$ rule is a concept suggesting that Blank$\_\_\_\_\_\_.$

Multiple choice question.

$80$ percent of new products will be successful while $20$ percent will fail

$80$ percent of a target market will respond to a marketing action, while $20$ percent will not

$80$ percent of a firm's sales are obtained from $20$ percent of its customers

$80$ percent of the time a customer buys what he or she did last time, and $20$ percent of the time he or she switches brands