Final answer:
Based on the characteristics of elemental sulfur being a fine yellow-colored powder and sodium chloride being white cubic crystals, the given statements suggest that option C or option D is true.
Step-by-step explanation:
To determine which statement about the substances in Petri dishes C and D is true, we need to consider their descriptions along with a basic understanding of chemical classifications. Elements, like elemental sulfur, cannot be broken down into simpler substances and often have distinctive characteristics. Compounds, such as sodium chloride (table salt), consist of two or more elements chemically combined in fixed proportions and generally exhibit different properties from the individual elements that constitute them.
Sulfur is a yellow, non-metallic element, and pure sulfur is indeed often a fine yellow-colored powder. Sodium chloride is commonly known for its white cubic crystals. Without the exact content of the cable mentioned in the question, we can consider these general characteristics to address the possible statements.