Business managers are often concerned that just one of their company's activities will make or break their company's competitive advantage. However, you know that

a$.$ it depends on the industiy$-$sometimes this is true, sometimes it is not true.

b$.$ they are right; it is usually just one single activity that makes or breaks their competitive advantage.

c$.$ their company's success depends on an array of many key activities, not just one activity.

d$.$ they should worry more about their competitor's activities than their own company's activities.