A 7 kg suitcase and a 12 kg suitcase are dropped from the same second story window at the same time. If there is no wind resistance, which of the following sentences is true? Select one:
a. The 7 kg suitcase will hit the ground first.
b. The 12 kg suitcase will hit the ground first.
c. The suitcases will hit the ground at the same time.
d. It is impossible to predict what will happen