Given the task definition and input, reply with output. 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". 

[header] How to make a theremin [title] Learn the essential components of the theremin. [step] A theremin is basically a box with two antennas, one of which controls the pitch of the instrument, the other of which controls the volume. These antennas create electromagnetic fields which are " played " by manipulating them with the hands. <sep> (A) They are tuned and manipulated using the head and antenna of your instrument. [substeps] The operation of this type of theremin is complicated. (B) The theremin usually goes in a box, so this is where the crankoperators come in handy. [substeps] The theremin is designed to perform various tasks on your instrument, such as transferring notes from string to a circle. (C) Coils of tight-pack wire act as oscillators, producing signals fed into the antennae. While it may seem like spooky magic, the fields are created by relatively straightforward circuitry. (D) Depending on the instrument size and equipment, each would produce a different pitch. [substeps] For a theremin you may want to order a set of around.

C