What does line coding allow devices to understand?

Line coding specifically refers to the method used to convert digital data into a format suitable for transmission over various types of media. This process involves representing binary data as electrical or optical signals that can be understood by the devices involved in communication.

The correct choice focuses on "the electrical charge states as zero and one," which is fundamental to line coding. In line coding, binary digits (0s and 1s) are represented as specific voltage levels or states, where typically '0' might correspond to a low voltage (or absence of voltage), and '1' to a high voltage. This allows devices to accurately interpret the binary information being transmitted.

Other options may address related concepts but do not precisely describe the primary function of line coding. For example, how to send and receive data is more about the overall communication protocol, converting digital data into analog signals relates more to modulation techniques than line coding specifically, and the format of data storage pertains to data organization rather than the transmission format that line coding provides. Thus, the emphasis on electrical charge states in the correct answer encapsulates the essence of what line coding achieves.