Explanation:
intransitive verb................
Depression
According to The National Institute of Mental Health, an estimated 3.2 million adolescents in the United States had at least one major depressive episode in 2017. That means about 13% of teenagers may experience depression before reaching adulthood.
Answer:
The correct answer for this question is D) Over time the sand bed will become plugged with dirt and require a cleaning process known as backwashing.
Explanation:
This sentence best fits at the end of the topic as it explains that one stage of the maintenance process is the backwashing of the item.
