(c)
This comes nearer being logical, as it shows one Spade trick, and, therefore, indicates help for a partner's Royal, but with that exception, it is subject to the same objections as "b." It is troublesome to take out, and when compared with "d" gives extremely limited information.
It may, however, be of distinct advantage for a player who does not approve of light No-trumpers. Followers of the theory that the call of one No-trump means four or five sure tricks will certainly find "c" or even "b" an advantageous system, but the advantage of "getting to the No-trump first" is so manifest that the light declarations have become generally popular, and but few of the "I-will-not-declare-unless-I-have-the-'goods'" bidders are now to be found.
If a player believe in calling No-trump with the minimum strength now considered sufficient, he has little use for either "b" or "c."
It is self-evident that "c" cannot be used as often as "b," so the Declarer who likes always to say something will prefer "b," but the bidder who wishes, when he calls, to have distinct value attached to his announcement, will elect in favor of "c" rather than "b," and for the same reason will find "d" the best system of all.
(d)
It is toward this system that the evolution of modern bidding is turning. True, two Spades cannot be declared as frequently when "d" is used as when "b" or "c" is employed, but the "d" bid conveys information so comprehensive and important that one call is of greater value than several "b" or "c" bids, which, at best, furnish the partner with indefinite data.
It makes the weakness take-out of the partner, namely, one Royal, easy and logical, and in every way seems the soundest, safest, simplest, and most conducive to game-winning of all the plans suggested.
It invites equally the two most important declarations, makes easy the position of the partner when he holds long, weak Spades, and is doubtless destined, in a short time, to be the only two-Spade system in use, unless it be found advisable to include in the repertory of the original declarer both "b" and "d."
This can be readily accomplished by calling two Spades for "b"; three Spades for "d"; and four Spades for the combination hereinafter given, for which the declaration of three Spades is suggested.