VsbsvbsbsvavssvsbsbavzbcdvzbsbsbbnMksnsbssvbsbzbsbsjwkkwjwbsbsnznzbzbnznakakwkwjwbbwbbebbz nakakaiwkwkw
W= l - 5 where w = width and l = length
area = 84 = l*w = l(l-5)
l(l-5) = 84
l^2 - 5l - 84 = 0
(l - 12)(l + 7) = 0
l = 12
length = 12 and width = 7
M is your answer, because the tangent intersects the circle at point M.
So M is correct.
