Final answer:
The correct expression for the probability of the union of independent events is 1-(1 - p)¹⁵.
Step-by-step explanation:
To find the probability of the union of independent events, you can use the formula P(A₁ UA₂ U... U A₁₅) = 1 - (1 - p)¹⁵. This means that the probability of at least one of the events occurring is equal to 1 minus the probability that none of the events occur. So, the correct expression is a. 1-(1 - p)¹⁵.