Explanation:

When the customer aims to track both agent performance and customer satisfaction, the best functionality to use is Reports & Dashboards. These tools offer real-time, visual insights into operational metrics, performance KPIs, and customer feedback — enabling managers to make data-driven decisions and optimize service delivery.

🅰️ Option A: Field History Tracking
Field History Tracking allows you to monitor changes to specific fields in Salesforce objects — such as when a case status changes or who updated a field. While helpful for auditing and compliance, it doesn't offer a comprehensive view of agent performance or customer satisfaction. It lacks visualization, aggregation, and interpretation — making it a supporting tool, not a primary reporting solution for performance tracking.

🅱️ Option B: Reports & Dashboards ✅ (Correct Answer)
Salesforce Reports & Dashboards are core tools that allow organizations to:

✔️ Track agent metrics like case resolution time, first call resolution, average handle time, and number of cases closed.
✔️ Monitor customer satisfaction via CSAT scores, Net Promoter Scores (NPS), or customer survey feedback.
✔️ Visualize trends and KPIs in real-time with dynamic charts, tables, and filters.
✔️ Empower leadership and supervisors to make informed decisions using accurate and live data.

These tools are easy to customize, require no coding, and are integrated across Service Cloud, making them ideal for tracking the exact business outcomes the customer cares about.

🅲 Option C: Einstein Discovery
Einstein Discovery is an advanced AI-powered analytics tool that uses machine learning to provide predictive insights and recommendations based on large datasets. While it can forecast trends (like predicting churn or case volume), it’s more suited to strategic analysis than day-to-day operational monitoring. It may add value in conjunction with dashboards, but it's not the primary tool for tracking current agent performance or immediate customer feedback.

🅳 Option D: Process Builder
Process Builder is an automation tool used to automate workflows, such as updating fields, sending alerts, or launching flows based on criteria. It helps streamline backend processes but does not provide reporting or analytics functionality. It’s excellent for improving operations but cannot generate insights into how agents are performing or how customers feel about their experiences.

🧩 Summary:
To monitor agent performance and customer satisfaction, Reports & Dashboards (Option B) provide the most accessible, scalable, and powerful functionality within Salesforce. They turn raw data into actionable insight, allowing organizations to improve service quality and meet performance goals.

📚 Official Salesforce Reference:
🔗 Salesforce Reports & Dashboards Overview