Which of the following is a longitudinal wave?

The figure below shows pressure variation in two different sound waves in air with time at a given position. Both the figures are drawn to the same scale. Which of the following statements is true?

$A$ $SONAR$ (sound navigation and ranging) uses ultrasonic waves to detect and locate objects under water. In a submarine equipped with a $SONAR$,the time delay between generation of a probe wave and the reception of its echo after reflection from an enemy submarine is found to be $77.0\; s$. What is the distance of the enemy submarine (in $; km$)? (Speed of sound in water $= 1450\; m/s$)

$A$ plane wave of sound traveling in air is incident upon a plane surface of a liquid. The angle of incidence is $60^{\circ}$. The speed of sound in air is $300 \ m/s$ and in the liquid it is $600 \ m/s$. Assume Snell's law to be valid for sound waves.

When pressure on a gaseous medium is changed at constant temperature,what will be the effect on the speed of sound wave in it?

An earthquake generates both transverse $S$ and longitudinal $P$ waves in the earth with speeds $4.5 \,km/s$ and $8.0 \,km/s$, respectively. $A$ seismograph records that the first $P$-wave arrives $3.5 \,min$ earlier than the first $S$-wave. From the seismograph, the epicentre of the earthquake is located at a distance of: (in $\,km$)