Wilson, Xavier, Yoeman and Zenger were playing a card game, in which three cards, from each player's holding, remained to be played; and in which one of the four suits - clubs, diamonds, hearts, and spades (denoted respectively as C, D, H and S)- was the high suit. A high suit is just like a trump suit in many card games.

The play of four cards, one from each player's holding was a trick, and the suit of the card played first in a trick was the suit led.

[1] The distribution of the four suits on the cards held by the four players was as follows:

Wilson's  holding -- C   H   D
Xavier's  holding -- C   S   S
Yoeman's  holding -- C   H   H
Zenger's  holding -- S   D   D

[2a] A player had to play a card in the suit led, if possible, at each trick.
[2b] If [2a] is not possible, he had to play a high suit.
[2c] If [2b] is also not possible, then he could play any card.
[3] Each of the remaining three tricks contained in part: the suit card led, just one other card in the same suit as led, and a high suit card which won the trick.
[4] A player who won a trick had to lead at the next trick.

Which suit was the high suit?