(PLEASE HELP ME) Melissa is testing the effects of different sand formations near beaches on wave
patterns by making scale models and conducting a controlled experiment. In her
investigation, which variable should be changed and which should be held
constant?
A. changed variable: shape of sand formations, constant variable: amount of water,
speed of waves
B. changed variable: pattern of waves; constant variable: shape of sand formation,
amount of water
C. changed variable: pattern of waves; constant variable: speed of waves, amount of
water
D. changed variable: speed of waves, constant variable: shape of sand formations,
smouont of water