Answer & Explanation
C) Decrease in density impulse
Density impulse is the specific impulse of the propellants multiplied by its density. Addition of small inert solid particles will increase the density of the propellant and hence lead to improved impulse density. This also means that the volume required to store the propellants is lesser and the rocket size becomes smaller. It will lead to drag reduction (since the surface area is lesser) under atmospheric operating conditions and improve speed and range of the vehicle.