Statement-I : sound waves of frequency less than 20Hz is not audiable to human beings.
Statement-II : infra sonic waves are produced during earthquakes.

Options

A. Statement -I is true, Statement -II is true and
Statement -I is correct explanation for Statement -II.
B. Statement-I is true, Statement-II is true and
Statement -II is not correct explanation of Statement-I.
C. Statement-I is true, Statement-II is false and
D. Statement-I is false, Statement-II is false.

Answer

B

Explanation

Statement-I is true, Statement-II is true but Statement -II is not correct explanation of Statement. So correct choice is b.