You are given the initial velocity of an object at time t = 0, the velocity of the object at a later time , and the time interval t in which this change in velocity occurs. assuming constant acceleration, which equation can be used to find the total displacement of the object from time t = 0 to time

You have to be very careful how you interpret this question -- more specifically what you do about the acceleration. It's constant. That makes a usable even though the acceleration is not part of the equation.

You can't use b because it requires that you know the acceleration or distance to find the other. So don't choose b.

Again you need a value for the acceleration to find d. You have 2 unknowns and 1 equation. so C is out.

Same with D

A is your answer.

if you was gonna solve for a, a is a   < -12