Step 1: We need to find the state that is not counted among the classical endemic zones for kala-azar in India.
Step 2: Visceral leishmaniasis in India concentrates in the eastern belt, principally Bihar, West Bengal, Jharkhand and Uttar Pradesh.
Step 3: Of the four options, three - West Bengal, Uttar Pradesh and Bihar - fall squarely within this endemic belt.
Step 4: Assam is the one that lies outside this standard endemic grouping, so it is the exception.
\[\boxed{\text{Assam}}\]