For the following questions, statement as well as the reason(s) are given. Each questions has four options. Select the correct option.
(a) Statement $-1$ is true, statement $-2$ is true; statement $-2$ is the correct explanation of statement $-1$.
(b) Statement $-1$ is true, statement $-2$ is true but statement $-2$ is not the correct explanation of statement $-1$.
(c) Statement $-1$ is true, statement $-2$ is false
(d) Statement $-1$ is false, statement $-2$ is true
Statement $-1:$ When pressure in a gas changes, velocity of sound in gas may change. Statement $-2:$ Velocity of sound is directly proportional to square root of pressure.
(A) a
(B) $b$
(C) $\mathrm{c}$
(D) $\mathrm{d}$