The liquid part of a homogeneous mixture is the
a. solvent
b. solution
c. solute
d. colloid

The liquid part of a homogeneous mixture is most often than not the a. solvent

This depends on the type of homogeneous mixture at hand. For a liquid-solid homogeneous mixture, the liquid works as the solvent. For a gas-liquid homogeneous mixture, the liquid often works as the solvent as well. However, for a liquid-liquid homogeneous mixture, the liquid acts as both the solute and solvent.