Bloody sunday served as a turning point in russia because

Ait marked the beginning of world war i.
Bit strengthened the tsar’s power.
Cit caused the people to lose faith in the tsar.
Dit led to japan’s triumph over russia.

Verified Answer :

C
There were riots against Tsar Nicholas II and this was something that hadn't happened as much in the past.  People were no longer "worshiping" the tsar and lost some respect for him