1. If two statements contradict each other, both cannot be true at the same time.
2. In logical reasoning, a tautology is always true.
3. A contradiction is always false.
4. A contingency is sometimes true, sometimes false.

Correct option is C

Solution:
· Statement 1: Correct — contradictory statements cannot both be true.
· Statement 2: Correct — a tautology is always true for all cases.
· Statement 3: Correct — contradictions can never be true.
· Statement 4: Correct — contingencies are true in some cases, false in others.
All four are valid logical facts.
Correct Answer: (c)