Which of the Following Is Not an Example of Horizontal

Which of the following is not an example of horizontal integration?

A) America Online and Time Warner merge to become AOL Time Warner.
B) Coca Cola buys most of its previously independent bottling firms.
C) Microsoft acquires Rare, Ltd., maker of video games such as Donkey Kong.
D) Georgia Pacific, a wood products firm, is combining operations with another wood products firm, Louisiana Pacific.
E) Citicorp Bank and Travelers Insurance merge to form Citigroup, a diversified provider of financial services.