Question

saltwater is a: pure substance heterogeneous mixute homogeneous mixture element

Explanation:

Saltwater consists of salt dissolved in water. A homogeneous mixture has a uniform composition throughout. Since salt uniformly dissolves in water in saltwater, it fits the definition of a homogeneous mixture. A pure substance has a fixed composition (like an element or compound), which saltwater is not. A heterogeneous mixture has visibly different parts (not the case here). An element is a pure substance made of only one type of atom (saltwater has multiple substances).

Answer:

homogeneous mixture