Concept:Probability is the ratio of favourable outcomes to total possible outcomes.Explanation:A fair die has six faces numbered 1,2,3,4,5,6.So, total possible outcomes =6.The favourable outcome for obtaining 4 is only one face, i.e. 4.Thus, favourable outcomes =1.Probability=Total outcomesFavourable outcomes=61Answer:The probability of obtaining 4 is 61, which is option A.