Renewable resources need to be conserved because a) we are using them faster than they are replenished by nature

b)they are slowly disappearing from the Earth

c) if we overuse them nature will stop replacing them

d) all of these

(A) We are using them faster than they are replenished by nature

c)as speed changes, wavelength and frequency change.

everything changes!

the first american roller coaster was the mauch chunk switchback railway, built in the mountains of pennsylvania in the mid-1800s. the track, originally built to send coal to a railway, was reconfigured as a "scenic tour."