A service team manages their field technicians in Salesforce CRM connected to Marketing Cloud.

Comprehensive and Detailed Explanation:

The correct answer is B — Configure a Journey with API Event Entry Source, triggered by Process Builder.

Because the Appointment object doesn’t directly relate to Contact, Process Builder (or Flow) in Salesforce CRM can be used to fire an API Event to Marketing Cloud when an appointment is scheduled.

The Journey will then handle sending the notification and updating the "Confirmation Sent" checkbox.

❌Why others are wrong:

A: Salesforce Data Entry Source requires a direct relationship (Contact or Lead) — which is missing here.

C: Data Extension Entry Source needs a manual or scheduled import — not real-time.

D: Salesforce Send with Automation Studio would not provide immediate real-time notification based on appointment creation.

Exact Extract from Salesforce Official Documentation:

Salesforce Help — API Event Entry Source for Journey Builder:

"Use API Events to inject contacts into a journey from external or Salesforce sources where no direct object relationship exists, enabling real-time processing and communications."

(Source:https://help.salesforce.com/s/articleView?id=sf.mc_jb_api_event_source.htm )