According to the passage, companies ----.

Most large firms have marketing or advertising
departments that work in conjunction with their
advertising agencies. Only one part of the company's
sales budget will be spent through the advertising
agency. Companies have their own sales force for
calling on wholesale and retail organizations. In
many cases, they also produce a proportion of their
sales literature and shop display material. But with
the larger companies sales promotion efforts are
usually combined under a single marketing policy.
which is often worked out by the company itself in
conjunction with its advertising agency. The
advertising agency may also be consulted over
packaging systems and the distributing of new
products that are being put on the market.