Q.Find the odd one out:

A number series follows a single hidden rule (a constant difference, a constant ratio, or a changing pattern in the differences) that must be identified before finding a missing or next term. Coding-decoding applies a fixed transformation rule (a letter-shift, a position-number substitution, or a reversal) uniformly to every letter of a word, and the rule is worked out from a given example before being applied to a new word. Odd man out asks for the one item, among a group that mostly shares a common property, that fails to share it. All three are solved by writing the working explicitly (differences, letter-by-letter code, or the shared property in words) rather than guessing.