Answer:
The correct answer is:
dropped from 35% to 16%
Step-by-step explanation:
attached to this answer is a copy of the WHO figure showing Percentage of deaths due to each major cause, world, 1970-2015. From the graph, it is seen that for infectious diseases, the percentage of deaths was at 35% in 1970, but by 2015, it fell to 16%, I denoted this with red circles and a blue arrow on the left hand side of the plot.
The reason for this fall in percentage of death could be attributable to the increase in medical and pharmaceutical interventions as the years progressed. The discovery of a more broader spectrum antibiotics that were more effective against a wide strain of bacteria, the introduction of combination antimicrobial therapy, the improvement of general hygiene around the world, by the development of more effective cleaning agents etc. Also the advancement of molecular diagnostics e.g. the Polymerase chain reaction (PCR), has helped to sequence the genetic makeup of most common infectious agents helping for the development of more agent specific antibiotics.
Generally, improvement in intervention to infectious disease causing agents have led to the fall in the global death toll from these agents over the years.