An object is dropped into a fluid. The object initially sinks until it stops about halfway in the fluid when it starts to float. This occurs because the density of the fluid increases with depth and the object reached a depth where

the density of the object is less than the density of the surrounding fluid

the density of the object and fluid are the same.

the density of the object is greater than the density of the surrounding fluid

the object increases in size due to the pressure of the fluid