In 2015, there were about 22 million teenagers in the United States.
They each sent an average of 900 text messages per
month.
About how many text messages did all of the teenagers in
the United States send each month?
Express your answer using scientific notation.

i think c. but don't trust it.

step-by-step explanation:

large crystals result from very slow cooling.

evaporation of water: this would produce an evaporite which is a sedimentary rock. like a salt pan in a desert. not possible to have volcanic rocks originate this way.

crystalization in molten earth: slow cooling over time. (hundreds to millions of years)

crystalization at earth's surface: this results in fast cooling. (a few hours to a few months or years)

crystalization from cooling off hot water: that would be a hydrothermal deposit. while associated with volcanics they are not volcanic rocks themselves and usually occur fairly rapidly.