TASK DEFINITION: You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.
PROBLEM: Category: GREAT ALEXANDERS 
Clue: In 1990 Russia restored citizenship to this Nobel Prize-winning author of "Cancer Ward"

SOLUTION: aleksandr solzhenitsyn

PROBLEM: Category: SIMILES 
Clue: The expression this "as a judge" dates back to around 1700

SOLUTION: sober

PROBLEM: Category: CLASS "E" 
Clue: Often paired with public health, it's the branch of medicine that deals with outbreaks of infectious diseases

SOLUTION:
epidemiology