#1 The minimum legal age to take part in surveys
16 years – in a lot of countries you are allowed to take part in paid surveys at the age of 16. Just check out one of the survey sites and find out if you can choose your date of birth within the registration process. If so, you are eligible to join this site. If not try another one from the ones linked here
The survey sites featured in the article linked above are legit and driven by serious companies.