What is the difference between a vector and a scalar?

a. A vector is only used in measuring forces, a scalar is only used in measuring mass
b. A vector measurement is required for distance, a scalar measurement is required for displacement
c. A vector measurement contains a direction and magnitude, a scalar measurement only contains a magnitude
d. 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