If $F1$, and $F2$ are propositional formulae/expressions, over same set of propositional variables, such that $F1,F2$ both are contingencies, then which of the following is/are necessarily false(i.e. Never Possible):
- $F1 \vee F2$ is a contingency.
- $F1 \vee F2$ is a tautology.
- $F1 \vee F2$ is a contradiction
- $(F1 \rightarrow F2) \vee (F2 \rightarrow F1)$ is contingency.