Which type of transmission sends multiple bits simultaneously?

The correct answer is parallel transmission because it is specifically designed to send multiple bits of data at the same time across multiple channels or wires. This means that for every clock cycle, a number of bits equal to the width of the data bus can be transmitted simultaneously. This is particularly useful for short distances within a computer or between components where speed is critical, such as the connection between a CPU and RAM.

In contrast, serial transmission sends the bits one after another over a single channel. While it is often used for long-distance communication due to its simplicity and reduced interference, it transmits only one bit at a time, making it slower compared to parallel transmission for short distances.

Binary transmission refers to the encoding of data in two states (0s and 1s), which does not refer to the method of transmission but rather to the type of data being sent. Hexadecimal transmission serves as a higher-level representation of binary, often used for representation of data in a more compact form, but it also does not describe a transmission method.

Therefore, parallel transmission stands out as the method that sends multiple bits simultaneously, making it the correct choice for this question.