The characteristics of buyer$-$seller relationships exist on a continuum. On one extreme, there is $\_\_\_\_\_\_\_\_\_\_\_,$ where the parties are fully integrated as one unit. On the other extreme, $\_\_\_\_\_\_\_\_\_\_\_\_,$ where there are single short$-$term contracts that present minimal risk to both parties.

Select one:

a$.$

vertical integration $/$ open$-$market

b$.$

horizontal integration $/$ vertical integration

c$.$

open$-$market $/$ horizontal integration

d$.$

open$-$market $/$ vertical integration

e$.$

vertical integration $/$ horizontal integration