Concept:The rule is: cube the first number and add 3 to get the second number.Explanation:For the pair X:346, we have X3+3=346.So, X3=346−3=343.Since 73=343, we get X=7.For the pair 9:Y, apply the same rule.Thus, Y=93+3=729+3=732.Therefore, X=7 and Y=732.Answer:Option C: X=7,Y=732