Consider the decision diagram below. How many of the following statements must be true?

I. Uncertainty B has been observed at the time of Decision D$.$

II$.$ Uncertainty B has been observed at the time of Decision E$.$

III. Uncertainty A has been observed at the time of Decision E$.$

IV$.$ Uncertainty C has been observed at the time of Decision E$.$

Group of answer choices

$0$

$1$

$2$

$3$

$4$