The PDF Exam Guide is no longer available. Fortunately I was able to find a copy to share this sample question along with a discussion of which answers are right or wrong and why.
The sales manager at Universal Containers wants to see all Opportunities that do not have any activities.
Which two report types could be used to meet this requirement?
Choose two answers:
A. A custom report type with Opportunity as the primary object and Activity as the secondary object.
B. An Opportunity report with a cross-object filter of Opportunities without Activities.
C. A joined report using an opportunity report in Block A; a task and event report filtered by tasks for Block B.
D. A standard Opportunity report filtered where the field Last Activity is blank.
Resource: Retired Advanced Admin Exam Guide - https://developer.salesforce.com/resources2/certification-site/files/SGCertifiedAdvancedAdministrator.pdf