What is GSR composed of?

The correct answer highlights the nature of Gunshot Residue (GSR), which primarily consists of particles generated during the combustion of gunpowder when a firearm is discharged. These residues typically include elements such as lead, barium, and antimony, which are released during the firing process. This composition makes the first option accurate, as it addresses the specific source of GSR.

Other options focus on different aspects that do not accurately characterize GSR. For instance, while the chemical composition of firearm materials might encompass a broader scope, it fails to pinpoint the specific residues created by discharging a weapon. Similarly, residues from weapon storage conditions are unrelated to the instant action of firing and therefore do not contribute to GSR. Finally, stating that GSR consists solely of metal fragments from discharged ammunition does not provide a complete picture, as GSR includes many more components beyond just metals. Thus, focusing on the particles from the partial combustion of gunpowder provides the most precise understanding of what GSR entails.