which of the following is correct

a)the average speed of an object is the elapsed time divided by the distance traveled
b)the average velocity of an object is the ratio of the distance traveled by the elapsed time.
c)the instantaneous velocity is the limit of the average velocity, as elapsed tlme tends to zero.
d)All of the above are not correct
e) the vector position is the derivative of the instantaneous velocity

b)the average velocity of an object is the ratio of the distance traveled by the elapsed time.