Which are the three focus areas for reinventing the WAN? (Choose three.)

'Execution' is a broad term relating to implementation but not a specific technical focus area for WAN reinvention.

Centralized device authentication is an important security feature but is typically a component or enabler within 'Secure Elastic Connectivity' rather than a standalone, overarching focus area for WAN reinvention.

Secure Elastic Connectivity focuses on building a WAN that is both highly secure and flexible, adapting to changing business needs and connecting various endpoints and cloud resources reliably and safely.

Application Quality of Experience (App QoE) emphasizes ensuring that critical applications receive optimal performance, prioritizing traffic, and utilizing the best path selection to deliver a superior user experience over the WAN.

Cloud First networking recognizes the shift to cloud applications and services, requiring the WAN to provide direct, optimized, and secure access to cloud environments, reducing backhauling and improving efficiency.

'Operations' refers to how the network is managed, which is certainly impacted by WAN reinvention, but it's an outcome or a characteristic of a modernized WAN, not a primary focus area driving its design like the other three.