Q: 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 oxide concrete [title] Select your color. [step] There are a multitude of oxides available that you can add to concrete. Choose from red, light brown, dark brown, yellow, and black, among other colors. <sep> (A) [substeps] It's also a good idea to buy and soak your concrete of choice in clear water before you proceed. A homemade infusion can be rubbed across concrete with plastic or glass. (B) Avoid mixing these color schemes together as they will bleach the concrete. [title] Label concrete with a " h " or " gb. (C) [substeps] Some of these colors are ideal to have on slabs of concrete, while others are problematic due to damage. Either leave this option out, or slightly paint the concrete slightly-colors like blue can be hazardous to you and your skin. (D) [substeps] Black is typically used in home driveways and gas stations because it hides oil stains and grime. Brown hues are common in industrial flooring and some homes.
A:
D