In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D".

[header] How to work out water tank capacity [title] Measure the radius of the circle at the bottom of the cylinder. [step] The region enclosed by the circle at the bottom of the cylinder is your bottom base surface (b). A radius is any line segment that runs from a circle's center to its perimeter. <sep> (A) To find the radius, simply measure from the mid-point of the cylinder's bottom to the outside of the circle. [substeps] A diameter is any straight line segment that passes through the center of the circle and has endpoints on the circle's perimeter. (B) Your bottom base surface area is an inverted circle with a diameter that looks like this. [substeps] You don't have to measure the diameter all the way around the space you are working in but remember that this will help you determine the diameter of the circle. (C) [substeps] The diameter of your top base area is the diameter of your water tank. To create additional rgb of space around the base area, the diameter of your top base is 5 ft (1.8 m). (D) [substeps] When measuring the radius of your container, you can use this guideline for helping you accurately determine its yield. [title] Get an existing container that will accommodate your chemical mixture.
A