Assertion (A): Chills are used to reduce shrinkage porosity.Reason (R): the function of chill is to increase the rate of solidification in a critical region.

• A. Both A and R is correct, and R is a correct explanation for A
• B. Both A and R is correct, and R is an incorrect explanation for A
• C. A is wrong but R is correct
• D. A is correct but R is wrong