Which of these statements is true? a. there was a causal relationship between economic

Which of these statements is true?
a. there was a causal relationship between economic chaos and
increased food production.
o
b. there was a causal relationship between submarine warfare and
new shipping technology.
o
c. there was a causal relationship between world war i and a
worldwide outbreak of disease.
o
d. there was a causal relationship between medical advancements
and the influenza outbreak.