The first large-scale International Peace Conference was held at the Hague in 1899. At this conference all of the following were forbidden except what?

(a) Bombs dropped from balloons
(b) Torpedoes shot from underwater vessels (submarines)
(c) Bullets which expand in the body (dum-dum bullets)
(d) Poisonous gas
[xyz-ihs snippet=”Intl-Law-MCQs”]