Instructions: 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".
Input: [header] How to introduce a pleco to a goldfish tank [title] Ask how large the pleco will grow to be. [step] Although most pet stores will sell plecos that are only a few inches in length, you should know that they can grow quite large. Fully grown plecos can reach up to two feet in length. <sep> (A) [title] Check your tank's surface before you place the pleco into the tank. [step] Make sure that your aquarium is opaque or has a drop-down tray so that your pleco is not exposed to water. (B) This can have a negative impact on their lifespan. [title] Choose a tank with large walls and no air holes. (C) [title] Make sure you cover more than twice the tank. [step] If you find that your pleco grows too much, cover the entire tank with a blanket. (D) The exact size of the pleco will vary depending on the species. Ask someone at the pet store how large the pleco will get before making a purchase.
Output:
D