Why Did Rockefeller Ultimately Reorganize Standard Oil as a Holding

Why did Rockefeller ultimately reorganize Standard Oil as a holding company in the late nineteenth century?

A) To control competition by purchasing the production facilities of competitors and shutting them down
B) To purchase and hold the assets of competitors so that those competitors had no capital or collateral to use for expansion
C) To legally combine competing companies under a central administration
D) To minimize competition by investing heavily in both the production and the distribution of products