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 fall asleep if you are blind or visually impaired [title] Talk to your doctor. [step] If you are a blind or visually impaired person who is having trouble falling asleep, you should set up an appointment with your doctor. Ask your doctor to examine you for non-24, a sleep disorder that frequently affects visually impaired and blind people. <sep> (A) This can help you make a diagnosis and develop strategies to speed up your recovery. [substeps] Ask your doctor if sleep loss, depression, dyslexia, or dyslexia problems might be the issue and advice you need. (B) A doctor can make a diagnosis of a sleep disorder and understand your problem. Treatment of the sleep disorder based on the condition will help your doctor identify the underlying cause and decide how long it is necessary to treat you. (C) Your doctor may refer you to an optometrist or psychologist who has experience treating dementia or cognitive dysfunction. Your doctor may want to examine you in several places or diagnose various medical conditions. (D) [substeps] Non-24 is a disorder that affects your sleep-wake cycles and is common in blind people. People with non-24 have trouble falling and staying asleep at night, as well as extreme urges to nap during the day.
[EX A]: D

[EX Q]: [header] How to treat your customer while serving them [title] When the customer approaches your till point, greet them nicely. [step] This means you should acknowledge the customer with eye contact. Say " hello " and smile. <sep> (A) [title] Apologise for any wait, no matter how short. [step] The customer might not understand why they have had to wait. (B) [substeps] Also greet them in a professional manner. Always state your name, address, and similar things. (C) Offer him or her a fresh drink once in awhile. [substeps] Remember to shake each customer's hand. (D) If you don't meet their smile they'll get bored and start saying no. To greet the customer again, do a brief " hi " and introduce them to your horde.
[EX A]: A

[EX Q]: A woman is standing on an elliptical machine. she <sep> (A) pushed the red button. (B) - she is doing rows of pumps in the gym. (C) starts working out on the machine. (D) pushes the chair back and starts doing exercise on it.
[EX A]:
C