Four players-W, X, Y, and Z-play a series of games. In each game the four form two pairs that play against one another; one pair wins and one pair loses.

    When a pair wins or loses a game, both players are credited with the win or the loss.

    Games are played in a series in which partners are changed with each game until all possible combinations of partners have played. The series begins again repeating the combinations of partners in the same order.

    16. Which of the following is a possible sequence of partners for W?

    (A) X, Z, Y, X, Y, Z

    (B) Y, X, Z, X, Z,Y

    (C) Y, Z, X, Y, Z, X

    (D) Z, X, Y, Z, Y, X

    (E) Z, Y, X, Y, X, Z

    17. In order that all possible combinations of partners play one game each, how many games must be played?

    (A) 3

    (B) 4

    (C) 5

    (D) 6

    (E) 8

    18. If each player has won at least one game, what is the minimum number of games that must have been played?

    (A) 1

    (B) 2

    (C) 3

    (D) 4

    (E) 5

    19. At the end of the third game in the first series, which of the following must be true?

    (A) There is a player who has won two games and lost one game.

    (B) There is a player who has won all three games.

    (C) There is a player who has lost two or more games.

    (D) There are three players who have lost exactly one game each.

    (E) There are three players who have won exactly two games each.