Help with question's A-D please

A: Label each wave above as transverse or longitudinal.
B: Which wave above could be used to represent a sound wave?
C: Which wave above is used to represent an electromagnetic wave?
D: Which wave above is also a model for light waves?

Automobile fuel efficiency is often measured in miles that the car can be driven per gallon of fuel (mpg). heavier cars tend to have lower fuel efficiencies (lower mpg ratings). which variable (weight or fuel efficiency) is most naturally considered the explanatory (predictor) variable in this context?