When investing in direct mail, diminishing returns apply after
a. $700,000 per product.
b. $700,000 per segment.
c. $800,000 per product.
d. $800,000 per segment.
e. $500,000 per product.
a. $700,000 per product.
b. $700,000 per segment.
c. $800,000 per product.
d. $800,000 per segment.
e. $500,000 per product.