The most accurate statement is Inclusion and exclusion criteria are always needed in some form.
Inclusion criteria are the prospective subjects characteristics that should be taken into consideration in the study.
Exclusion criteria are set of predefined definitions commonly used to identify subjects who will not be included or those characteristics that disqualify prospective subjects for the study to be included
The one that you've circled (A) is the correct answer.
Answer:
Create an air gap to prevent backflow.
Explanation:
An air gap prevents contamination of the water because it creates a space between the water outlet and a contaminated source. So, if there is, for example, a decrease in the pressure that pumps the water to the faucet, the water the air gap will prevent the contamination of potable water and the cause of different illnesses.
