Step-by-step explanation:
Speed : It is defined as the overall distance travelled by an object divided by total time taken. The mathematical expression is given by :

It is a scalar quantity i.e. it has only magnitude.
Velocity : It is defined as the total displacement (D) of the particle divided by total time taken. It can be given by :

It is a vector quantity. It have both magnitude and direction.
Out of given options, the statement that best explains the difference between velocity and speed is (B) i.e. "Velocity is a vector and requires a direction to completely describe it".