Which of the following statements about decision trees is true?
a. Evaluate and choose among candidate decision trees based on their performance on the cross validation data, not the training data they were built from.
b. The more branches a tree has, the more precisely and correctly it will make predictions.
c. Decision trees should take into account all available data on a topic, even data which is unavailable at the time a choice is to be made.
d. To make accurate predictions, decision trees need to be fully built out so that all nodes are pure.