Please help I have been stuck on these homework question for a long time!!

a)

Consider the wave shown below. Point Z, marked by the black dot, is a particle in the medium that is currently at its equilibrium position. If the wave shown is moving to the right, in which direction is point Z currently moving? C A B Z D Ediagonally down and right down up right it is at rest diagonally up and leftWhich of the following accurately describes the Doppler effect?As an object emitting a sound approaches an observer, the sound waves become compressed, so that the observer hears a lower frequency. As an object emitting a sound approaches an observer, the sound waves expand, which reduces their energy and dampens the noise. As an object emitting a sound approaches an observer, the sound waves expand, so that the observer hears a higher frequency. As an object emitting a sound approaches an observer, the sound waves become compressed, so that the observer hears a higher frequency