B. Both Assertion and Reason are true, and Reason is not the correct explanation for Assertion
C. Assertion is true, but Reason is false
D. Assertion is false, but Reason is true
Cholera toxin binds to ganglioside on intestinal mucosal cell, which leads to ribosylation of the alpha subunit of Gi protein.
This results in the inhibition of the inherent GTPase activity and irreversible activation of Gi Protein. Therefore adenyl cyclase remains active and keeps cyclic AMP levels high. This prevents the absorption of salts from the intestine leading to watery diarrhea and loss of water from the body.