The correct answer is: C. bit
A bit is the smallest unit of information in computing and digital communications. It is a binary digit, the basic unit of information in computing and digital communications. A bit can be either 0 or 1, corresponding to the electrical values of off or on, respectively.
A byte is a group of eight bits. A nibble is a group of four bits.
Binary-Coded-Decimal (BCD) numbers express each digit as a group of four bits, or a nibble. This means that each digit in a BCD number can be represented by one of the following values: 0000, 0001, 0010, 0011, 0100, 0101, 0110, 0111, 1000, 1001, 1010, 1011, 1100, 1101, 1110, or 1111.
For example, the BCD number 123 would be represented as 0011 0010 0011.
BCD numbers are often used in applications where it is important to maintain the accuracy of decimal data, such as in accounting and financial systems.