To speed up the communication from the top managers down to the lower$-$level employees and vice versa, a CEO :vould most likely

a$.$ reorganize the chain of command, thereby decreasing the flatness of the company.

b$.$ decentralize the company, thereby changing it from a tall organization to a flat organization.

c$.$ expand the chain of command, thereby increasing the tallness of the company.

d$.$ centralize the company, thereby changing it from a flat organization to a tall organization.