Final answer:
Decision tree probabilities refer to the probability of an uncertain event occurring.
Step-by-step explanation:
Decision tree probabilities refer to the probability of an uncertain event occurring. Decision trees are a visual representation of possible outcomes and associated probabilities.
For example, imagine you have a decision tree to predict whether it will rain tomorrow. The decision tree may have branches for different factors like temperature, humidity, and wind speed, each with their own probabilities. By following the branches, you can calculate the overall probability of rain.
Therefore, option (a) "an uncertain event occurring" is the correct answer.