It should be the answer b but I’m not to sure
Density = mass / volume
Density = (45g) / (9 [volume units])
Density = 5g / [volume unit]
There was no specification on the units of volume. However, whatever it may be, just replace the square brackets with the value and your units will be correct.
A scientific theory focuses on explaining a phenomenon, while a law will have a generalised statement about said phenomenon. Often times, we use laws to help us develop theories. =)
I believe the answer is C