To defend their merchant ships against attacks from german submarines, the allies a. began shipping supplies using zeppelins. b. suspended the transport of supplies by ship. c. organized the merchant ships into convoys. d. resorted to trench warfare.

In order to protect themselves against the German u-boats, the Allied powers suspended the transportation temporarily of various supplies to their troops abroad, which ultimately led to some disastrous consequences as a result of running low on crucial necessities.

The answer is B Slaves freed after the civil war