Planets are massive, so we use models to easily view our solar systems in schools and homes.
Answer;
B. Water purification programs
Explanation;
The goal of hygiene promotion is to help people to understand and develop good hygiene practices, so as to prevent disease and promote positive attitudes towards cleanliness.
Hygiene promotion encompasses a systematic attempt to adequately promote personal, domestic, environmental and food hygiene practices that prevent or mitigate the transmission of diseases. Water purification programs is among the government programs that encourages hygiene practices.
The answer is Nitrification.
The answer to your question would have to be C