The correct equation for the density \( D \) of an object is given by:
\[ D = \frac{m}{V} \]
where:
- \( D \) is the density,
- \( m \) is the mass of the object,
- \( V \) is the volume of the object.
So, the response \( D = \frac{m}{V} \) or \( D = m / V \) is correct.