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". 

[Q]: [header] How to choose a protein supplement [title] Choose whey protein to build muscle. [step] If you're looking for muscle-building protein, whey protein is generally your best option. Whey protein can come in the form of powder or pills and is commonly used when people are trying to build muscle via things like weight training programs. <sep> (A) By doing this, you're gaining more body fat and growing more muscle at the same time. [substeps] Whey protein can be found in half of the packaged foods. (B) Whey protein is also a low-fat protein, rich in red blood cells from bacteria. Although whey protein does not impart healthy fats to the body, whey protein helps build muscle, which you can grow and burn through exercise. (C) [substeps] Look for a whey protein powder or supplement with a high biological value. This measures how well your body can absorb the protein. (D) Whey protein occurs as a food chain, hence the slogan, " protein is fat free ". [substeps] Whey protein is complex and varies from patient to patient.
[A]: C


[Q]: [header] How to travel abroad [title] Do your research. [step] You need to research where you are going, the flight times and prices for airlines, and which documents you need to take with you. Plan out your itinerary carefully. <sep> (A) Some cities, like london or paris, really need a week to see what they have to offer. Travel times also need to be taken into consideration. (B) For example, visit a couple of websites of airlines to see what type of itinerary they offer. Pay attention to the price, name, phone number and/or mailing address of each airline. (C) This will help ensure that all of your research enables you to see where you want to go. [substeps] Do research on an airline's website, and see what seat guides they offer on planes and what websites they provide online. (D) [title] Decide whether you will be flying from 1 area or from another. [step] International flights should likely be just a teaser.
[A]: A


[Q]: A man is talking to the camera. he <sep> (A) is holding a tuber and cutting it with a ruler. (B) then demonstrates how to mold parchment paper into a frame. (C) is wearing a pair of black glasses. (D) is shown on a boat, paddling.
[A]:
C