Which of the following is a vector quantity?
speed
distance
acceleration

C) Acceleration
For example, if person A is the observer, then he/she can predict the distance or speed or time by simply looking at it. But at the same time, the observer can't predict the acceleration of a moving object as he/she can't determine the direction of the object. So, without a direction, the acceleration can't be predicted. For example, displacement, force, velocity, momentum, etc. are vector quantities.
◙ But, Distance, speed and time are only specified with their magnitude. For example, work, volume, density, mass, etc. don't need a direction for their representation.
So, (c)Acceleration is the answer.