Final answer:
Immediate causes of undernutrition, as defined by the UNICEF conceptual framework, directly impact the individual's nutritional status and do not act at the household level; thus, the statement is false.
Step-by-step explanation:
The statement 'According to the UNICEF conceptual framework, "immediate" causes of undernutrition act on the household level' is false. Immediate causes refer to inadequate dietary intake and disease, which are factors that directly affect the individual's nutritional status. While household-level factors indeed play a critical role, they fall under the category of "underlying" causes according to the UNICEF framework. These underlying causes include inadequate access to food in households, poor household care behaviors, and inadequate health services and unhealthy environment—factors that determine the health and nutritional status of individuals within those households.