Questions: The marginal cost curve intersects the average total cost curve at: - its lowest point. - its maximum. - its end point. - no point; the curves don't intersect.

The answer is the first one: its lowest point.

Explanation for each option:

1. Its lowest point: This is correct. The marginal cost (MC) curve intersects the average total cost (ATC) curve at its lowest point. This is because when the marginal cost is less than the average total cost, the average total cost is decreasing. When the marginal cost is greater than the average total cost, the average total cost is increasing. Therefore, the point where the marginal cost equals the average total cost is the lowest point of the average total cost curve.

2. Its maximum: This is incorrect. The intersection occurs at the lowest point of the average total cost curve, not at its maximum.

3. Its end point: This is incorrect. The curves intersect at the lowest point of the average total cost curve, not at its end point.

4. No point; the curves don't intersect: This is incorrect. The marginal cost curve does intersect the average total cost curve at its lowest point.

In summary, the marginal cost curve intersects the average total cost curve at its lowest point.