The increased risk of melanoma in the group of teenagers studied was due to: 
The pronoun “they” in line (5) refers to: 
The researcher Ulf Wester suggests, when using a sun bed: 
The pronoun “they” in line (4) refers to: 
The word “bout” can be substituted by: 
The survey showed that: 
Amteto D’ Amicis believes that: 
It’s correct to say, according to the text that: 