CORRECT answer is 'of.'The given sentence is saying something about the BOY and the disease typhoid.The use of the word ''cured'' in the sentence indicates relieving of a person or animal of the symptoms of a disease or condition.Therefore, the most appropriate preposition to be FILLED in the blank is 'of'.'Of' is used for expressing a cause.Example: He was now completely cured of his illness. Hence, the correct answer is OPTION 2.Complete Sentence: The boy was cured of typhoid. Let us explore the other options:'From' MEANS indicating separation or removal.'For' is used for stating the purpose of an object or action.'Through' means continuing in time towards completion of a process or period.