An australian study showed that cell-phone use while driving was associated with slightly more than a fourfold increase in crash risk (odds ratio 4:1).

wavelength variability is the right one

i believe the answer would be:

d. violin, clarinet, french horn, and tuba

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.