K.E = 1/2 mv²
800 = 1/2 ×12 ×v²
800 = 6 v²
800 / 6 = v²
= 133.4 =v²
√133.4 = √v²
11.5 = v²
I hope this answer is correct.
I believe C is your answer (also, I am also using tht same exact program!)
According to the Jefferson lab, "The scientific definition of work is: using a force to move an object a distance (when both the force and the motion of the object are in the same direction.)"