How could a role in which all users must specify an index=clausein all searches be configured?

How could a role in which all users must specify an index=clausein all searches be configured?
A . Set the authorize.confsetting: srchIndexesDefaultto no value.
B . Set the authorize.confsetting: srchFilterto no value.
C . Set the authorize.confsetting: srchIndexesAllowedto no value.
D . Set the authorize.confsetting: srchJobsQuotato no value.

Answer: B