Scientists wanted to learn the mystery behind his death.
Personally, I would choose D. You should always make a good first impression of someone.
If a person abruptly stops an intense cardio workout without cooling down, then an aneurysm and heart attack may occur.
Answer: C
Cardio means heart so you can eliminate D. When you work intensely and abruptly stop you weaken the artery wall which will cause an aneurysm.
