Which data type is an unsigned 1-byte type that stores values from 0 to 255?

• A. unsigned long
• B. volatile
• C. unsigned char
• D. highByte()

Answer: (C)

Understanding how an 8-bit unsigned integer works helps you pick the right type. An unsigned 8-bit value can store 256 different patterns, giving a range from 0 up to 2^8 − 1, which is 255. The type that exactly fits this description is unsigned char, which uses 1 byte of storage and represents nonnegative values from 0 to 255.

The other options don’t match: unsigned long is typically 32-bit, with a much larger range (0 to 4,294,967,295). volatile isn’t a data type by itself; it’s a qualifier that tells the compiler not to optimize accesses to a variable. highByte() is a function, not a data type, and it doesn’t define storage size or range.