Final answer:
New sample containers for solids testing are rinsed with isopropyl alcohol (C) to ensure accurate testing and remove potential impurities or residues from previous samples.
Step-by-step explanation:
In order to ensure accurate testing, new sample containers for solids are typically rinsed with isopropyl alcohol (C). Isopropyl alcohol is commonly used as a cleaning agent in laboratories due to its ability to effectively remove contaminants without leaving behind residue. By rinsing the sample containers with isopropyl alcohol, any potential impurities or residues from previous samples can be eliminated, preventing any interference with the testing process.