Answer:
the evolutionary time between two nodes
Explanation:
Branch lengths indicate genetic change i.e. the longer the branch, the more genetic change (or divergence) has occurred
Clinical trial of dubious quality to test his hypothesis about vitamin C; a clinical trial that other researchers rated as defective. In his research, there was not even a randomization to take vitamin C or not, it was simply observed the three who were given the micronutrient, without having a subject who was not given to compare results.