Answer:
Smoking ciggies is known too cause cancer
Sunbathing has little risk but can cause skin damage, but tanning can cause cancer.
Malnutrition has a a high chance of cancer
X ray expose can but only in really high dosage (not the ones used in hospitals)
Step-by-step explanation:
I would say that if 4 is talking more about The X ray´s used in hospitals and medical equipment, go with that one.