Answer: 2 n - 1.
- A 2<sup>n</sup>
- B 2<sup>n</sup> - 1
- C n!
- D n
Correct answer: B. 2<sup>n</sup> - 1
Explanation: Total subsets = 2<sup>n.</sup> Excluding empty set: 2<sup>n</sup> - 1 ways to select at least one object.
Counting tree for selecting 2 items from {A, B, C} without repetition: 3 x 2 = 6 ordered arrangements.
Concept context
Counting, arrangements, and selections