Answer:
Beach sand, a substance that contains rock, shells, metals, and other substances distributed unevenly throughout.
Explanations:
What are heterogeneous mixtures?
Heterogeneous mixtures are mixtures that consists of two or more substances with separate components or non-uniform compositions. These compositions vary from one region to another with at least two phases that remain separate from each other.
From the given options, simple syrup is homogenous since it consists of a mixture of similar substances (two-part sugars), sulfur is an element while carbon monoxide is a compound that consists of two elements, carbon, and oxygen.
Therefore the only heterogeneous mixture is beach sand since it consists of rock, shells, and metals which are non-uniform compositions, distinct substances possessing different chemical properties.