Is bronze an element, compound, mixture, or solution?
Bronze is a solution. Yes, I know that we usually think of solutions as liquids, but solutions can be gases, liquids, or solids. Bronze is tin dissolved in copper. If you dissolve zinc in copper you get a different solution called brass. Solutions involving metals are often called alloys.
Don't feel bad if you said bronze is a mixture, because you were right too. Solutions are a kind of mixture, where the components are homogeneous, mixed evenly throughout the substance.