Three students derive the derive the following equations in which x refers to distance traveled, v the

Question:

Three students derive the derive the following equations in which x refers to distance traveled, v the speed, a the acceleration (m/s2), and t the time, and the subscript (0) means a quantity at time t = 0:
(a) x = vt2 + 2at
(b) x = vot + ½ at2, and
(c) x = vot + 2at2.
What of these could possibly be correct according to a dimensional check?