My best guess would be the fourth answer because number one will leave out important information, number two could affect the distance and cause Smita to record incorrect distances due to the different speeds of the wind, number three makes sense, but what if Smita uses a different type of paper for an airplane in her procedure, the difference in the weight of the paper could cause one airplane to go farther while it causes the other airplane to fall faster. (I really hope this helps) >-<
