Why Correct: In computing, a word is the natural unit of data used by a particular processor design, measured in bits. While word size varies by architecture (e.g., 32-bit, 64-bit), 16 bits is specifically called a word in many contexts, especially in older 16-bit processor systems.
Distractor Analysis: A nibble is 4 bits, half a byte. A memory block is a larger, variable-sized unit of memory allocation, not a fixed bit combination. A byte is 8 bits, the standard unit for character encoding in most systems.
Takeaway: Common fixed bit groupings: 4 bits = nibble, 8 bits = byte, 16 bits = word, 32 bits = double word, 64 bits = quad word.