How can competitive advantage through IT be$$ sustained?

A$.$

It can be sustained by integrating all value creation processes into the organization.

B$.$

It can be sustained by suing any competitor whom your firm suspects is copying its systems.

C$.$

It can be sustained by using as many proprietary technologies as possible.

D$.$

It can be sustained by making all employees sign$$ non$-$disclosure agreements.

E$.$

Competitive advantage through IT cannot be sustained.