Assertion (A): If difference between static and optical dielectric constant is high, the mechanical compressiblity of that material is also high.Reason (R): For soft ions, ionic polarization per unit field is higher than that of hard ions.

• A. Both A and R are true and R is correct explanation of A
• B. Both A and R are true but R is not correct explanation of A
• C. A is true but R is false
• D. A is false but R is true