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". 

[EX Q]: [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.
[EX A]: D

[EX Q]: A small group of girls are first seen walking out on a gymnasium floor with several people watching on the sidelines. the girls <sep> (A) come together on a patch and begin performing dance moves with one another. (B) begin dancing and flipping with one another slowly back and fourth. (C) then perform a routine using batons while spinning and twirling. (D) then begin performing a routine on a step stool and ends with them getting back in the circle of walkers and dancing on the spot.
[EX A]: C

[EX Q]: [header] How to become an optometrist [title] Obtain a bachelor's degree in pre-med or science. [step] Before you can apply to an optometry program, you need to complete an undergraduate degree. Most optometry schools require coursework in biology, chemistry, physics, english, and mathematics. <sep> (A) A pre-med degree or degree in a biological science will help prepare you for med school. Get a well-rounded undergrad education and work hard to get good grades! Medical schools will want to see that you take your education seriously. (B) [substeps] College degree requirements for enrolling in an accredited pre-med program varies by state. Ask your guidance counselor if this is a good choice for you. (C) Depending on your interests, you may also want to complete a bachelor's degree in political science, cultural studies, and business. [substeps] Pursue something like a master's degree or a doctoral degree (bfa). (D) Then pass an exam which covers all four of these subjects and you will get a gpa. [substeps] An additional requirement might be having a master's degree in a specific subject, like biology.
[EX A]:
A