Which of the Following Best Defines Competitive Inertia

Which of the following best defines competitive inertia? 

A)  ​It is a reluctance to change strategies or competitive practices that have been successful in the past. 
B)  ​It is a competitive advantage that other companies have tried unsuccessfully to duplicate. 
C)  ​It is a discrepancy between a company's intended strategy and the strategic actions managers take when implementing that strategy. 
D)  ​It is a corporate-level strategy that minimizes risk by diversifying investment among various businesses or product lines.