Which of the following is a unit in the metric (SI) system?

• A. meter
• B. inch
• C. pound
• D. gallon

Answer: (A)

Verified step by step guidance

1. Understand that the metric system, also known as the International System of Units (SI), is a standardized system of measurement used worldwide in science and most countries.
2. Recall that the SI system includes units for length, mass, volume, and other physical quantities, with base units such as meter (length), kilogram (mass), and liter (volume, though technically not an SI base unit).
3. Identify the units given in the problem: meter, inch, pound, and gallon.
4. Recognize that 'meter' is the SI unit for length, while 'inch' is a unit from the imperial system, 'pound' is a unit of mass in the imperial system, and 'gallon' is a unit of volume in the imperial system.
5. Conclude that the correct answer is 'meter' because it is the only unit listed that belongs to the metric (SI) system.