Answer:
C. at least several
Step-by-step explanation:
Competitive advantage refers to a favorable situation or position a business enjoys over it's competitors owing to it's specialization or strength in performing a specific operation.
For example, in case of telecommunication, one company's competitive advantage could be superior network coverage with lower call drops than it's competitors.
In order to survive and grow, a business should try and gain competitive advantages in at least several fields and yet at the same time retain and maintain those competitive advantages over a period.