To associate multiple Engineering_Support__c records to a single Opportunity and display aggregate information on the Opportunity:
Option B: Master-detail field from Engineering_Support__c to Opportunity Master-Detail Relationship: Creating a master-detail relationship from Engineering_Support__c (detail) to Opportunity (master) allows multiple support records to be related to one Opportunity.
Aggregate Information: Master-detail relationships support roll-up summary fields, enabling aggregate calculations (like COUNT, SUM) on the Opportunity object based on related Engineering_Support__c records.
Reference:
"You can create roll-up summary fields on the master object in a master-detail relationship."
- Salesforce Help: Roll-Up Summary Fields Overview
Why Other Options Are Incorrect:
Option A: Lookup field from Opportunity to Engineering_Support__c
This would allow only one Opportunity to be associated with one Engineering_Support__c, and does not support roll-up summary fields.
Option C: Master-detail field from Opportunity to Engineering_Support__c You cannot create a master-detail relationship from a standard object (Opportunity) to a custom object in this direction.
Option D: Lookup field from Engineering_Support__c to Opportunity
Lookup relationships do not support roll-up summary fields, so aggregate information cannot be displayed on the Opportunity.