To override the Account's standard Edit button in Lightning Experience:
Option A: Lightning component
Implementation:
The Lightning component must implement lightning:actionOverride interface.
<aura:component implements="lightning:actionOverride, force:hasRecordId" access="global">
<!-- Component code -->
</aura:component>
Reference:
"To override standard actions, create a Lightning component that implements the lightning:actionOverride interface."
- Lightning Aura Components Developer Guide: Override Standard Actions
* Why Other Options Are Incorrect:
Option B: Lightning actions are used for quick actions, not for overriding standard buttons.
Option C: Lightning Flow cannot directly override standard buttons.
Option D: Lightning pages are layouts and cannot override buttons.