Multiple$-$choice questions

When we have multiple ads to show, what sequence is it suggested we use?

a$.$ Expose all the ads simultaneously in one period.

b$.$ Expose one ad first for a period of time, before exposing the next.

c$.$ Expose one ad first for a period of time until it wears out, before exposing the next.

d$.$ Split the media budget amount to have four ads in one burst, before exposing the next four.

e$.$ None of the above.