What was Dr. Willem Johan Kolff’s first step in using the scientific process to invent the hemodialysis machine?

The scientific process begins with an observation or question. Kolff saw a patient whose kidneys had failed and wondered whether an external machine could do the kidneys’ work. That question was the starting point for his investigation, so the correct choice is “When a patient’s kidneys failed, he wondered if it would be possible to perform kidney functions with an external machine.”

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