What was the major objective of public health nutrition advice during the first 75 years of the past century (1900’s) in the u. s.?

Public heath nutrition advice comprises organized efforts to improve the health of communities. The major objective of public health nutrition is to control transmissible diseases, reduction of environmental hazards, and provision of safe drinking water because communal, environmental and biological aspects cooperate to define health, public health practice must develop a wide-ranging set of skills and interventions. 

Ithink it's a, but i might be wrong