How does the Doppler effect cause a siren's pitch to increase as it approaches you?

A. Sound waves are spread out, increasing wavelength and
decreasing frequency.

B. Sound waves are pushed closer together, increasing wavelength
and decreasing frequency.
C. Sound waves are spread out, decreasing wavelength and
increasing frequency.

D. Sound waves are pushed closer together, decreasing wavelength
and increasing frequency.

According to newton's second law, when the same force is applied to two objects of different masses, a the object with greater mass will experience a great acceleration, and the object with less mass will experience an even greater acceleration, b. the object with greater mass will experience a smaller acceleration, and the object with less mass will experience a greater acceleration, c. the object with greater mass will experience a greater acceleration, and the object with less mass will experience a smaller acceleration, d. the object with greater mass will experience a small acceleration, and the object with less mass will experience an even smaller acceleration.

Which features on mars point to the possibility of liquid water on the planet? impact craters with sharp rims volcanic cones with craters gullies and stream-like channels mountain ranges with faults

How does the kinetic energy of a charge change as the charge moves under the effect of an electric field from higher potential to lower potential? a.the kinetic energy increases.b.the kinetic energy decreases.c.the kinetic energy remains the same.d.the kinetic energy is always zero.