Which metric prefix corresponds to a value of 1?

• A. none (base unit)
• B. kilo
• C. milli
• D. centi

Answer: (A)

Verified step by step guidance

1. Understand that metric prefixes are used to denote multiples or fractions of base units in the metric system.
2. Recall that the base unit itself has no prefix and corresponds to a value of 1 (for example, 1 meter, 1 gram, or 1 liter).
3. Recognize that 'kilo' means 10^3 (or 1000 times the base unit), 'milli' means 10^-3 (or one-thousandth of the base unit), and 'centi' means 10^-2 (or one-hundredth of the base unit).
4. Since the question asks for the prefix corresponding to a value of exactly 1, identify that this means no prefix is used, which is the base unit itself.
5. Conclude that the correct answer is 'none (base unit)' because it represents the value of 1 without any multiplication or division.