Assuming this is multiple choice, the answer would be "niche". An organism's niche is where that certain organism fits into an ecosystem, or what their part to play is.
The best thing to do is to rinse the dust cap with freshwater and dry it with a clean towel of air from the tank. Be sure to blow or towel dry the dust cap before putting it in place on the first stage.
The United States flag will always go on top. Typically you leave approximately one foot of space between the United States flag and the flag underneath.
B... cause that’s the only one for that.
