|A) Both A and R are true and R is the correct explanation of A.||B) Both A and R are true but R is NOT the correct explanation of A.|
|C) A is true but R is false.||D) A is false but R is true.|
When in winter, hot water is poured in the glass tumbler. its inner surface tends to expand while the Outer surface in contact with cold atmosphere does not. This opposite interaction causes the tumbler to break.