According to$-$the $\frac{80}{20}$ rule, which of the following is true?

$20$ percent of a product's customers account for $80$ percent of the product's marketing expenditures.

$80$ percent of a product's customers account for $20$ percent of the product's marketing expenditures.

$80$ percent of a product's marketing cost should be equal to $20$ percent of the firm's total marketing budget.

$80$ percent of a product's market should be consumers who are $20$ or older.

$80$ percent of a product's sales come from $20$ percent of the product's purchasers.