(A) Precision
Precision is defined as the percentage of true positive cases out of all cases where the prediction is positive (predicted true).
Precision = True Positives / (True Positives + False Positives). It measures how many of the predicted positive cases are actually positive. Recall, by contrast, measures true positives out of all actual positives. Students often confuse the two — remember: Precision is about the quality of positive predictions.