Which of the following statements are true? <br> 1. Frequency of the vibration of a particle is defined as number of vibrations completed by the particle in one second. <br> 2. Wave motion is the sort of disturbance which travels through the medium. <br> 3. Velocity of sound in dry air is grater than the velocity of sound in moist air <br> 4. Seismic waves are examples of mechanical waves

Question

$\begin{array}{1 1} (a)\; \text{1, 2 and 3} \\ (b)\; \text{2, 3 and 4} \\ (c)\; \text{1, 3 and 4} \\ (d)\; \text{1, 2 and 4} \end{array}$