In the Present Universe,the "Mass Density" of Radiation,using Einstein's Equation

In the present universe,the "mass density" of radiation,using Einstein's equation E = mc² for the photons,is:

A) essentially zero since there is very little radiation left in the universe at the present time.
B) much greater than the mass density of matter leading to a radiation-dominated universe.
C) equal to the mass density of matter since these parameters have remained balanced throughout the evolution of the universe as a consequence of the equipartition of energy.
D) much less than the mass density of matter, leading to a matter-dominated universe.