Universal Containers wants to track installation information once a container has been purchased on a...

The new custom object (“Installation__c”) must store installation details that are related to an Opportunity. Since each installation should be tied directly to a single opportunity, and inherit ownership and visibility from that opportunity (as per “sales reps should have visibility”), a Master-Detail relationship is appropriate.

Why B (Master-Detail) is correct:Exact Extract:“In a master-detail relationship, the detail record inherits the sharing and security settings of its master record.” — Salesforce Help | Relationships OverviewBecause Opportunities already have ownership and sharing settings that determine sales reps’ visibility, making Installation__c the detail record ensures that sales reps automatically see related installations.Exact Extract:“The master-detail relationship closely links objects so that the master record controls certain behaviors of the detail record, such as record ownership, sharing, and deletion.” — Salesforce Help | Master-Detail Relationships

Why B (Master-Detail) is correct:Exact Extract:“In a master-detail relationship, the detail record inherits the sharing and security settings of its master record.” — Salesforce Help | Relationships OverviewBecause Opportunities already have ownership and sharing settings that determine sales reps’ visibility, making Installation__c the detail record ensures that sales reps automatically see related installations.Exact Extract:“The master-detail relationship closely links objects so that the master record controls certain behaviors of the detail record, such as record ownership, sharing, and deletion.” — Salesforce Help | Master-Detail Relationships

Why not A (Many to Many):Many-to-many relationships are only used when multiple records on both sides need to relate (e.g., Opportunities linked to multiple Installations and vice versa). That is not described here.

Why not C (Hierarchical):Hierarchical relationships are only available on the User object.

Why not D (Lookup):Lookup relationships do not automatically grant visibility or inherit ownership, so sales reps might not see all related installations.

References (Salesforce Platform App Builder documentation / Study Guide topics):

Salesforce Help | Relationships Overview

Salesforce Help | Master-Detail Relationships

Salesforce Platform App Builder Exam Guide | Data Modeling and Management