The correct answer is: B. At its lowest point.
The marginal cost curve intersects the average cost curve at its lowest point because at that point, the marginal cost is equal to the average cost. This means that the additional cost of producing one more unit is equal to the average cost of all the units that have already been produced. This is the most efficient point to produce at, because the cost of producing each additional unit is equal to the average cost of all the units that have already been produced.
Option A is incorrect because the marginal cost curve intersects the average cost curve at its lowest point, not to the left of it.
Option C is incorrect because the marginal cost curve intersects the average cost curve at its lowest point, not to the right of it.
Option D is incorrect because the marginal cost curve intersects the average cost curve at its lowest point, not at its maximum point.