Which of the following describes the wave speed of all waves? A. the speed of light
B. the speed at which the disturbance propagates
C. the speed at which particles that transmit the wave are moving
D. the rate at which the wave oscillates back and forth

B.the speed at which the disturbance propagates

a great example would be sound. In air, the speed of sound is about 343m/s, but in iron, the speed of sound is about 5120 m/s that's about 15 times faster than air. Why is this? Well, it is because in the air the molecules are very spread out and have a long way to travel before they can bump their neighbors. But in iron, the molecules are much much closer and have a shorter distence before they hit their neighbors.

causes

fossil fuels burn

cities become more industrialized

human population grows worldwide