You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. you have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent. i. treating the substance with nucleases that destroy all nucleic acids and then determining whether it is still infectiousii. filtering the substance to remove all elements smaller than what can be easily seen under a light microscopeiii. culturing the substance by itself on nutritive medium, away from any plant cellsiv. treating the sample with proteases that digest all proteins and then determining whether it is still infectiouswhich treatment could definitively determine whether or not the component is a viroid? a) ib) iic) iiid) ive) first ii and then iii