The owner of a music store is planning a window display of five products. Three are to be CDs selected from K, L, M, N and O and two are to be DVDs selected from R, S, T and U. The display items are to be selected according to the following conditions: (1) If K is displayed, U must be displayed. (2) M cannot be displayed unless both L and R are also displayed. (3) If N is displayed, O must be displayed, and if O is displayed, N must be displayed. (4) If S is displayed, neither T nor U can be displayed. If K and T are the first two display items to be selected, how many acceptable groups of items are there that would complete the display?

Explanation: (A) Display must include K (CD) and T (DVD). Since K is selected, U must be selected (Condition 1). The two DVDs are {T, U}. Since U is selected, S cannot be selected (Condition 4). The CD set must have 3 items from {K, L, M, N, O}. K is already selected. We need 2 more CDs from {L, M, N, O}. R is the only remaining DVD (but we have T and U). Since R is not selected, M cannot be selected (Condition 2). The remaining CDs must be from {L, N, O}. We need 2 CDs. Possible pairs are {L, N}, {L, O}, {N, O}. Since \(N \iff O\) (Condition 3), {N, O} must be selected together. If {N, O} are selected, the CD set is {K, N, O}. The full display is {K, N, O, T, U}. This is one acceptable group. If L is selected, N and O must be excluded, but we need 3 CDs. Thus, the only acceptable group is {K, N, O, T, U}. The total number of acceptable groups is 1.