Which best explains why blood is considered to be a suspension?
a)it has nutrients that cannot be dissolved
b)it contains particles that can settle out.
c)it has nutrients that are dissolved in its liquid portion.
d)it contains particles that mix on a molecular level.

I think the best answer is b): it contains particles that can settle out.

The definition of suspension is a heterogeneous (that is same in all parts) mixture that contains particles that could undergo sedimentation (settle down) - this definition is close to b). It should not matter whether those particles are nutrients( so A or C are not good answers).

It’s the energy source of stars