Concept:The sequence rises by 4 up to the middle term, then falls by 4 symmetrically.Explanation:The given sequence is 138,142,146,150,?,142,138.From 138 to 150, each term increases by 4: 138+4=142, 142+4=146, 146+4=150.After the middle value 150, the sequence decreases by 4: 150−4=146, 146−4=142, 142−4=138.So the sequence is symmetric: the third term and the fifth term are equal.Therefore, the missing term is 146.Answer:The missing number is 146, which is Option C.