Availability is one of the key components of the CIA (Confidentiality, Integrity, and Availability) triad and refers to ensuring that data and services are available when needed. In this scenario, ensuring that the online store is accessible at all times, especially during a surge in traffic, directly relates to the concept of availability. While confidentiality ensures that data is not disclosed to unauthorized individuals and integrity ensures that data is not altered or tampered with, these concepts are not the primary focus in this scenario. Attack surface reduction is a concept that involves minimizing the number of opportunities for attackers to exploit, but it does not directly address the constant accessibility of the service.