Which Is a Barrier of Implementing Ecological Model Interventions

Which is a barrier of implementing ecological model interventions?

A) Multiple levels of intervention broaden options for intervention and slow down the process of selecting appropriate interventions
B) They are typically more expensive and time consuming compared to single-level interventions
C) There is little evidence that they are effective in changing health behaviors or improving health outcomes
D) The World Health Organization and the Centers for Disease Control and Prevention oppose funding ecological interventions