the lava and pyroclastic that erupted mount. sakuajima volcano consists of medium- K series and endesite - dacite .the composition clearly differ between eruption periods.
Well if you mean what does the controlled part of a scientific investigation, it is the part of the investigation that will be your control or your base, untouched, original, data and such.
This is a science question, but Thermosphere, Ionosphere, Mesosphere, stratosphere, troposphere
The answer is A..............100% sure