11-19. 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.