How can CK give guest users access to a custom object?

Cloud Kicks (CK) wants to create a public site to recruit potential volunteers. Volunteenng events are stored in a custom VolunteeringEvent object.

How can CK give guest users access to a custom object?
A . Through guest user roles
B. Through guest user Sharing Sets
C. Through guest user organization-wide defaults (OWD)
D. Through guest user Sharing Rules

Answer: D