Detailed 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".
Problem:[header] How to make cat jungle gyms and playgrounds [title] Gather boxes and tubes. [step] You will want as many sturdy boxes of different sizes as you can find. Cardboard boxes can be obtained for free from membership warehouse stores, liquor stores, furniture stores, discount stores, copy shops, toy stores, or grocery stores. <sep> (A) The boxes can also be used to build houses if you like, although they are much more expensive and require more time. The boxes you need are listed below in " things you'll need ". (B) Cardboard tubes can be salvaged from paper towels, wrapping paper, mailing tubes, and bolts of fabric. [title] Gather materials to hold the boxes together. (C) You will also need boxes for anyone who wants a scratching post. [substeps] Homemade trusses, balls, and potholder let you make playgrounds by banging a drum on a wooden platform. (D) Request boxes be sturdy, flat, and vertical so that they are easy to transport. [substeps] Try buying boxes with bars and barbells that you can rent from furniture stores.
Solution:
B