Answer:
D. Pilot error isPilot error is the most serious threat to aviation safety. Pilots could be better trained.
Step-by-step explanation:
We can construct the relative frequency distribution dividing the amount of incidents for each category by the total amount of incidents.
This amount is:
[tex]\sum x_i=627+64+113+382+481=1667[/tex]
Then, the relative frequency for each category is:
[tex]\text{Pilot error}=627/1667=0.38\\\\\text{Human error}=64/1667=0.04\\\\\text{Weather}=113/1667=0.07\\\\\text{Mechanical problems}=382/1667=0.23\\\\\text{Sabotage}=481/1667=0.29\\\\[/tex]
As the pilot error has the largest relative frequency, we can conclude that pilot error is the most serious threat to aviation safety.