The Hirschman-Herfindahl Index (HHI) in an Industry Is 50

The Hirschman-Herfindahl index (HHI) in an industry is 50. A merger is proposed that will raise the HHI to 100. In this case, the

A) Sherman Act will prohibit the merger.
B) Federal Trade Commission will challenge the merger.
C) Federal Trade Commission will not challenge the merger.
D) rule of reason will prevent the merger if it represents a horizontal merger.