It is determined whether an object will float or sink in a liquid by:

Density is defined as a body's mass per unit volume. We can also say how much mass it can fit into a given volume.

Iron, being a solid substance, takes up more mass in a given volume than wood.

It provides a mathematical formula.  $\mathrm{Density} \left(\mathrm{\rho }\right)= \mathrm{mass} \left(\mathrm{m}\right)/ \mathrm{Volume} \left(\mathrm{V}\right)$ 

An object's ability to float or sink is determined by its relative density to other objects.

If the object's density exceeds the density of the liquid, the object will sink.

On the other hand, if an object's density is less than that of the liquid, it will float above it.

When the density of an object and the density of a liquid are equal, they are in equilibrium and float and sink at the same time.

As a result, whether an object sinks or floats is determined by the density differential between the object and the liquid.

Option C is the right answer.