Koch's postulates are not applicable to

Assertion : Dope test is used to estimate the level of blood alcohol by analyzing the breath of persons drinking alcohol.

Reason : A drunken person usually feels tense and less talkative.

Assertion : Escherichia coli, Shigella sp. and Salmonella sp. are all responsible for diarrhoeal diseases.

Reason : Dehydration is common to all types of diarrhoeal diseases and adequate supply of fluids and electrolytes should be ensured.