Faster voyages across the atlantic ocean resulted in
a. an increase in smuggled africans
b. an increase in deaths of africans
c. a decrease in deaths of africans
d. a decrease in slavery

Faster voyages across the Atlantic Ocean resulted in "C. a decrease in deaths of Africans," since a main cause of death was enduring harsh conditions on board the ship itself during the "Middle Passage". It should be noted that many still died, however.