The correct answer is D because it matches the requirement of taking multiple snapshots per day and retaining them for one week. Option A is incorrect because it only takes one snapshot per day, which is not enough for the administrator's need. Option B is incorrect because it only retains the snapshots for one week, which means the older snapshots will be deleted after seven days. Option C is incorrect because it only takes two snapshots per week, which is not frequent enough for the administrator's need.
Reference: The following sources provide more information about the SLA retention policies and how to create and modify them in NDB:
Nutanix Database Management & Automation (NDMA) course, Module 4: Protecting Databases Using Time Machine, Lesson 4.1: Creating and Modifying SLA Retention Policies Nutanix Certified Professional - Database Automation (NCP-DB) v6.5, Knowledge Objectives, Section 5 - Protect NDB-managed Databases Using Time Machine Nutanix Database Service (NDB) User Guide, Chapter 6: Protecting Databases Using Time Machine, Section 6.1: Creating and Modifying SLA Retention Policies