Solution: Correct option 3. The statement talks about studies claiming that consumption of citrus fruit brings down the risk of having cancer and then an example is given. From what is supplied we only know that people who consume citrus fruit have a lower probability of developing cancer, but there is no assurance that they will never have the ailment. Therefore, inference 1 does not follow. Also from the statement, we cannot deduce that those who do not consume citrus fruits will necessarily have cancer. Therefore, inference 2 gets ruled out. Since grapefruit has been supplied as an example to back the research/claim it can be inferred that it is a citrus fruit. Therefore, inference 3 follows. Since the statement only talks about citrus fruits we cannot conclude about fruits in general. Therefore, inference 4 doesn't follow. Hence,option 3 is correct.