The correct option is D - 1000 J
Let the upward direction be positive
Force applied by the gravity is equal to the weight of the object, as the object is lifted slowly.
F = W = -mg
Minus sign shows that force is downwards
Displacement , s = 100 m
W = F s
W = - mgs
W=10×10×100=−1000 J
Since force and displacement are in the opposite direction, work done is negative.