Answer:
C. 1.5 m copper(II) sulfate(aq)
Step-by-step explanation:
I say this because a copper is a metal and a metal always has the highest melting and boiling point. A metal is also malleable, can dissolve in water, and a good conductor of electricity. All the other answers have all the nonmetals in them like Carbon, Oxygen, Chlorine, and etc. Nonmetals do not have a high boiling point. They basically are brittle. Therefore, the final answer is C.