Final answer:
The area under the curve calculator is used to find the area between a curve and the x-axis using integration.
Step-by-step explanation:
The area under the curve calculator is used to find the area between a curve and the x-axis. This is typically done by using integration, so the answer is A) Integration calculator. Integration is a calculus concept that involves finding the antiderivative of a function, which represents the area under the curve. By calculating the definite integral of a function within certain bounds, you can find the area between the curve and the x-axis.