Sentence:  Mostly, the microbiome is beneficial. It helps with digestion and enables people to extract a lot more calories from their food than would otherwise be <WSD>possible</WSD>. Research over the past few years, however, has implicated it in diseases from atherosclerosis to asthma to autism. 
Meaning of the word marked with <WSD> tags:  Capable of being done or achieved; feasible.