A. all the events are strictly judged to precise rules.
Explanation:
Not B since the X games are a US event.
Not C since the X games are held annually.
Not D since the events have been changed.
The answer could be Sleep deprivation because they would loose a lot of sleep thinking about the lose
Answer: 80-90%
Explanation: "Cigarette smoking is the number one risk factor for lung cancer. In the United States, cigarette smoking is linked to about 80% to 90% of lung cancer deaths. Using other tobacco products such as cigars or pipes also increases the risk for lung cancer." - cdc.gov