What does it mean for a solution to be saturated a. no more solute can be dissolved b. the concentration can be increased c. no more solvent can be dissolved d. the solution can dissolve more substances

A. No more solute can be dissolved 

Explanation:
A solute is defined as a substance that is dissolved
A solvent is the substance in which the solute is dissolved

When the maximum concentration of solute is dissolved in a solvent, the solution is said to be saturated.
This means that the any more solute added to the solution will not dissolve.

Hope this helps :)

A) the enthralling of formation for pure element in its standard state is always positivehope this : )

Both models are effective because they show the valence electrons, and these valence electrons indicate the reactivity of an element.