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 Input:
[header] How to relieve constipation after surgery [title] Use a stool softener. [step] One of the first medications to try if you're feeling constipated is a stool softener. These are easy to find over-the-counter and can help get you back on track. <sep> (A) [substeps] The way that stool softeners work is that they draw water into your stool from your intestines. This makes your stool softer and easier to pass. (B) [title] Take 600ml of stool softener before a meal. [step] Most stool softeners kill the production of prostaglandins. (C) [substeps] One good option for relieving constipation at the time of surgery is a stool softener. While stool softeners do provide temporary relief from constipation, they are expensive and will often disappoint you. (D) These medications are named for their antioxidant properties, which help reduce diarrhea and keep your stools from becoming irritated. [substeps] Remember that: the next time you're using an over the counter stool softener treatment, be sure to follow the dosing instructions.

Ex Output:
A


Ex Input:
[header] How to clean rubber boots [title] Wipe away light dirt and grime. [step] If your boots aren't especially dirty, you can usually clean them easily with a damp cloth. To prevent dirtiness from building up on your boots and causing longer cleaning times, do this after each time you use your boots. <sep> (A) Before handling an object or stepping on something wet, make sure you wipe it away on a rag first. Use a mild soap and water to wipe off even the smallest traces of dirt. (B) [substeps] To increase the dirt fighting potential of your damp cloth, mix 1 tsp (5 ml) of dish soap with a ¼ gallon (1 l) of water. Douse your rag in this, and wipe down the boots. (C) [title] Grind three pounds (177 g) of dry powder on a coffee grinder. [step] The dry powder will help to transfer dirt and dust to the boots. (D) This will clear little dirt and grime off of your boots, leaving them looking brand new. [substeps] If your boots are already cleaned, you may need to consult a shoe store or partner to inspect them for a better cleaner.

Ex Output:
B


Ex Input:
A girl flips and takes her turn then flips out of the center. A teen does a flip to the other side of the room. one of the teachers <sep> (A) comes and takes their places. (B) takes her turn next. (C) reaches down to help the girl who was standing up. (D) moves to the middle of the floor.

Ex Output:

D