What does the next steps within the activity timeline contains? Choose two answer

Answer options:

A.Activities fields
B.Scheduled Events
C.Tasks to complete
D.Chatter

Correct Answer B & C 
The next steps within the activity timeline contains are scheduled events and tasks to be completed. It displays the activities in chronological order from top to bottom. 
Options A and D are incorrect because the timeline doesn’t show the activities fields and the chatter. The activities fields are located on the activity page layout and the chatter is under a separate tab. 
Reference: 

https://help.salesforce.com/articleView?id=activity_timeline_customization_considerations_lex.htm&type=5