A solid cube of mass \( M \) and density \( \rho_c \) is held completely submerged in a container of liquid with density \( \rho_l \). The density of the cube is less than the density of the liquid (\( \rho_c < \rho_l \)). To keep the cube from rising to the surface, it is tethered to the bottom of the container by a thin, vertical string of negligible mass. Which of the following is a correct expression for the magnitude of the tension \( T \) in the string?