Which of the following is true of cholera-
Recent epidemic was due to classical type
Causes secretory diarrhoea
Caused by endotoxin
Vibriocidal antibodies correspond to susceptibility
Vibrio causes secretory diarrhea.

About Other options:

Recent epidemics are due to O1 ElTor and also O139 serovar. (Classical still exists and few cases were reported from Bangladesh)
Vibriocidal antibodies in serum (titer 1:20) have been associated with protection against colonization and disease. …………… Jawetz 25/e p237
Endotoxin (LPS) does not play any role in pathogenicity of cholera but is responsible for immunity developed by killed vaccine.