Ascientist is creating a new synthetic material. the material’s density is 6.1 g/cm3. which sentences describe how the scientist can lower the material’s density?

The density is the relation mass/volume.

Then you can modifiy the density of a material by either affecting the mass or the volume.

If you increase the volumen while keeping the mass constant, the density will decrease (because you are increasing the denominator of the fraction).

Also, you can decrease the mass while keeping the volume constant to decrease the density (because you are decreasing the numerator of the fraction).

Then the answer is decrease the mass or increase the volume, while the other is kept constant.