Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A) : Barium carbonate is insoluble in water and is highly stable.

Reason (R) : The thermal stability of the carbonates increases with increasing cationic size.

1. A Both (A) and (R) are true and (R) is the true explanation of (A) Correct answer
2. B (A) is true but (R) is false
3. C Both (A) and (R) are true but (R) is not the true explanation of (A)
4. D (A) is false but (R) is true.