Answer:
guaranteed to occur
Explanation:
An event that has a probability of 1 or in other terms P(E) = 1 is said to be guaranteed to occur. This is basically stating that the event has a 100% chance of happening, meaning that no matter what the external factors turn out to be in the scenario, the event will occur regardless. 1 basically represents 100%, while lower values such as 0.5 represent 50% when dealing with these probabilities.