Recent increases in downstream costs have occurred because of:

$1)$ Increased advertising and product promotion.

$2)$ Increased customer servicing.

$3)$ Increased competition.

$4)$ Increases in product design.

a$.1$ and $2.$

b$.2$ and $3.$

c$.3$ and $4.$

d$.1,2$ and $3.$

e$.2,3$ and $4.$