Why Has the Nineteenth Century Been Identified as "The Century

Why has the nineteenth century been identified as "the century of the child"?

A) Parents began having more children, and larger families required more attention.
B) Parents had a new attitude towards childhood, and families became child-centered.
C) Medical advances made it possible for more children to survive to adulthood.
D) Children became a more important part of the labor force.
E) For the first time ever, children began to spend money in the economy.