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 find the number of a blocked call [title] Get an private branch exchange (pbx) account. [step] One option is asterisk, a free, open source software. Another is switchvox. <sep> (A) This will also work better than 200 blackwire. If you buy one, it will work with the same account ($ 0.11). (B) The pbx is considered to be a free exchange. While this service typically does not have much use for a desktop account, it gives you access to many anonymous call accounts. (C) A pbx converts your computer into a telecommunications device and will allow you to manipulate incoming call data to identify blocked callers. [substeps] Before embarking on this method ensure that you thoroughly understand the technical challenge it presents and the potential financial burden it incurs. (D) Without switchvox here you are on better business. No other option is available to get a contact number from an online website.
[EX A]: C

[EX Q]: [header] How to make a cow cake [title] Shape the cakes. [step] You'll need a head, nose and ears to form the cow cake as a whole. Prepare each cake as follows : [substeps] Trim around the top rim of the smaller cake. <sep> (A) Then cut a crescent shape from one side. You should be left with a slightly off-centre oval shape. (B) Pinch the top rim of the larger cake closed. Make sure that the top rim is lined with icing. (C) You'll want to end up with six cakes. If you want a bigger cake, place the smaller cake on your table or set it on the rack. (D) Cut two holes around the circumference of the bowl side. Make a circle inside the side of the smaller cake.
[EX A]: A

[EX Q]: [header] How to avoid getting chicken pox while helping an infected person [title] Understand how the chickenpox virus spreads. [step] The virus is highly contagious and spreads in the air through airborne particles that come from the lesions on the skin or from the upper respiratory tract. You can also contract the virus from contact with open lesions when you touch your face, nose, or mouth. <sep> (A) While it is not contagious, the virus can spread if irritated by a scratch. [substeps] Eczema, for example, can occur due to jock itch or ingrown toenails. (B) [substeps] The disease takes 10 to 21 days after exposure to develop. From studies of transmission across household members, approximately 90% of people with close contact with infected individuals will develop the disease. (C) If you find yourself feeling ill while helping a patient, and the contagious virus is spreading to your body, or on them, contact the doctor right away. [substeps] The virus will spread through the individuals who touch their faces and mouths. (D) This bacteria is not a endemic virus and everyone may get it from someone else. [substeps] Let your doctor know that you are not sure about the hepatitis b virus.
[EX A]:
B