Select the correct answer.
auroras are lights that appear at earth’s northern and southern poles. what is the main cause of an aurora?

a.
solar wind enters earth’s atmosphere, and particles interact with ions.
b.
bubbles of gas are ejected from earth’s outer crust.
c.
sunlight reflects off the surface of the moon during an eclipse.
d.
the northern and southern poles are cool

Read the paragraph and answer the question that follows: the town of belmond, iowa, needs to add weather sirens. the loud and steady wail would warn citizens of approaching danger. if past history is an indication, the sirens will save hundreds of lives. with a prediction of a deadly storm season, the alert which sentence should be revised to eliminate redundancy? the town of belmond, iowa, needs to add weather sirens. the loud and steady wail would warn citizens of approaching danger. if past history is an indication, the sirens will save hundreds of lives. with a prediction of a deadly storm season, the alert system is needed immediately.