Step 1: Recall that the rainbow theme of Mission Indradhanush corresponds to seven colours, matching seven diseases the programme set out to cover.
Step 2: The seven are diphtheria, pertussis, tetanus, childhood tuberculosis, polio, hepatitis B and measles. Scan the options against this list: tuberculosis, measles and diphtheria all appear on it, but Japanese encephalitis does not. The one left out is therefore Japanese encephalitis, option C.
Step 3: Confirm by elimination - choosing tuberculosis, measles or diphtheria would be wrong because each is squarely within the original seven, leaving Japanese encephalitis as the only vaccine outside the core Indradhanush list.
\[\boxed{\text{Japanese encephalitis}}\]