What is the predominate acid found in the following fruits peaches blackberries apricots elderberries rhubarb?

The predominant acid found in peaches, blackberries, apricots, Elderberries, and rhubarb is citric acid. However, rhubarb is unique as it contains oxalic acid as its primary acid. While citric acid contributes to the tartness of most of these fruits, rhubarb's oxalic acid gives it a distinct sharp flavor.