Sublimation is a process in which the substance's phase transition occurs directly from solid to the gaseous phase. Hence, its a physical change not chemical.
Combustion is basically the reaction of the compound with oxygen, which is a chemical reaction, hence the chemical change.
Electrolysis is the process of chemical decomposition of a substance through passing electric current.
Rusting is a process involving the reaction of metals with moisture (air + water). Thus, it is a chemical change.
Hence, the answer is option A.