[单选题]
Substance A has a de0e 2qjrut1 ww6bs3lq3 4 c(omdnsity of $3.0 \; g/cm^{3}$ and substance B has a density of $4.0 \; g/cm^{3}$. In order to obtain equal masses of these two substances, the ratio of the volume of A to the volume of B will be equal to
