Density Formula Basics Steps:

• Recall that density measures mass per unit volume in a substance.
• Identify the standard formula: density equals mass divided by volume.
• Compare choices to the formula: mass / volume matches directly.
• Confirm units: density in g/cm³ or kg/m³ results from mass (g or kg) over volume (cm³ or m³).

Why A is correct:

• Density is defined as mass divided by volume (ρ = m / V), a fundamental formula in physics and chemistry.

Why the others are wrong:

• B adds mass and volume, yielding units like g + cm³, not a density measure.
• C adds volume and mass, same issue as B with mismatched units.
• D divides volume by mass, calculating specific volume (inverse of density), not density itself.

Final answer: A