Which is a tautology A T T F T F T F T T F F T B T T F T F F

Which is a tautology? A. T T F T F T F T T F F T B. T T F T F F F T T F F F C. T T F T F F F T F F F F D. T T T T F T F T T F F T

Solution

A tautology is a formula which is \"always true\" --- that is, it is true for every assignment of truth values to its simple components. You can think of a tautology as a rule of logic.

The opposite of a tautology is a contradiction, a formula which is \"always false\". In other words, a contradiction is false for every assignment of truth values to its simple components.

A. T T F T F T F T T F F T

B. T T F T F F F T T F F F

C. T T F T F F F T F F F F

D. T T T T F T F T T F F T

Individually none of them are tautologic