Final answer:
The symbol representing a salt from the given options is 'c. CaCl₂,' which is calcium chloride, a compound consisting of calcium and chlorine in a ratio of 1:2.
Step-by-step explanation:
The symbol that represents a salt is c. CaCl₂. Calcium chloride (CaCl₂) is a type of salt, which in its formula, has a calcium (Ca) ion bonded to two chloride (Cl) ions, making it a compound with a 1:2 ratio of calcium to chlorine. In contrast, the other options provided are not salts: (a) O₂ is a molecule of oxygen, (b) C₂H₂ is acetylene, and (d) C₆H₁₂O₆ is glucose.