Core Requirement for Physical Quantities

Steps:

• Define a physical quantity as a property like mass or time that can be measured.
• Express it using the formula: physical quantity = numerical value × unit.
• Identify that recording demands specifying the magnitude via a number.
• Confirm units add context but the numerical part is indispensable for quantification.

Why C is correct:

• Per the International System of Units (SI) definition, every physical quantity requires a numerical value to represent its magnitude precisely.

Why the others are wrong:

• A: Numerical values can include decimals or fractions, not just integers.
• B: Units are essential but need not be SI; consistent units from any system suffice.
• D: Units can be derived (e.g., newtons) rather than restricted to base units like meters.

Final answer: C