The requirement is to automatically grant record visibility to all users in a specific role (Service Manager) based on record criteria (“Opportunity Type = Service Agreement”).

This is a textbook case for a criteria-based sharing rule.

Why C (Criteria-Based Sharing Rule) is correct:Exact Extract:“A criteria-based sharing rule determines which records to share based on field values, rather than who owns the record.” — Salesforce Help | Sharing Rules OverviewYou can define the rule to share all Opportunities where Type = 'Service Agreement' with all users in the Service Manager role.Exact Extract:“Use criteria-based sharing rules to share records based on record field values with roles, roles and subordinates, or public groups.” — Salesforce Help | Criteria-Based Sharing Rules

Why C (Criteria-Based Sharing Rule) is correct:Exact Extract:“A criteria-based sharing rule determines which records to share based on field values, rather than who owns the record.” — Salesforce Help | Sharing Rules OverviewYou can define the rule to share all Opportunities where Type = 'Service Agreement' with all users in the Service Manager role.Exact Extract:“Use criteria-based sharing rules to share records based on record field values with roles, roles and subordinates, or public groups.” — Salesforce Help | Criteria-Based Sharing Rules

Why not A (Manual Sharing):Manual sharing requires a user to share each record individually — it is not automated.

Why not B (Owner-Based Sharing Rule):Owner-based rules share records based on who owns them, not on a record field value.

Why not D (Apex Sharing Rule):Apex sharing is used only when declarative sharing rules cannot meet the requirement. In this case, a standard criteria-based rule is sufficient.

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

Salesforce Help | Sharing Rules Overview

Salesforce Help | Criteria-Based Sharing Rules

Salesforce Platform App Builder Exam Guide | Security