Which of the following is the smallest unit of data measurement?

The smallest unit of data measurement among the given options is the kilobyte. A kilobyte is equal to 1,024 bytes which is significantly less than a megabyte, gigabyte, or terabyte.

To provide context, a megabyte is 1,024 kilobytes, a gigabyte is 1,024 megabytes, and a terabyte is 1,024 gigabytes. This demonstrates the hierarchy of data measurement, establishing that each unit up from the kilobyte represents a larger quantity of data. Therefore, the kilobyte is the foundational unit in this sequence, making it the smallest in comparison to the others listed.