In a group of five friends: Alice, Bob, Charlie, David, and Eva, Alice and Bob cannot be selected together. Charlie can only be selected if David is also selected. Eva can be selected only if Charlie is not selected. Which of the following combinations can be selected?
A, B, C, D, and E are five different colors: Red, Blue, Green, Yellow, and Black. If Red is not Blue, Blue is not Green, and Green is not Yellow, which color is not mentioned as being different from any other?
From the set of items: X, Y, Z, A, and B, the following conditions apply: X can be selected only if Y is selected. Z cannot be selected if A is selected. B can be selected regardless of other items. Which of the following selections is valid?