Convection currents are driven by differences in? •Mass
•Volume
•Density
•Weight

Density

Explanation:

The density, of a substance is its mass per unit volume. The symbol most often used for density is ρ, although the Latin letter D can also be used. Mathematically, density is defined as mass divided by volume: {\displaystyle \rho ={\frac {m}{V}}} where ρ is the density, m is the mass, and V is the volume

c. 75.7

i think that is the right