What is the difference between a vector and a scalar?

a
A vector measurement is required for distance, a scalar measurement is required for displacement
b
A vector is only measured in SI units, where scalars are only measured in US Customary units
c
A vector measurement contains a direction and magnitude, a scalar measurement only contains a magnitude
d
A vector is only used in measuring forces, a scalar is only used in measuring mass

c

A vector measurement contains a direction and magnitude, whereas a scalar measurement only contains a magnitude.