Question

Solutions are always
1.heterogeneous
2.homogeneous
3.both a and b

Answer 1

What's your textbook say? I imagine something like this:

A solution is a homogeneous mixture of two or more substances. A solution may exist in any phase.

For example:
- a solid solution is brass
- a liquid solution is aqueous hydrochloric acid (HCl in water)
- gaseous solution is air.

Answer 2

Ya, a solution is always supposed to be homogenous. It is one in which the solute particles are too small to be seen. For example, when you dissolve white NaCl in water, it decolourizes. That's because the particles of NaCl are too small to scatter any light in solution.
As you increase the particle size of the solute, it becomes a colloid or a suspension at a point. The size becomes so large that it scatters light and you can see the color. The particles do not completely dissolve in it. It is a mixture, not a solution. Mix flour in water, and try to dissolve. It wont, and the solution will acquire a characteristic color(This scattering of light is known as Tyndall effect)

Answer 3

a soution by definition would be homogenous