State which of the following collections are set:

(i) collection of odd natural numbers less than 50

(ii) collection of four colors of a rainbow

(iii) collection of the first three days of a week

(iv) collection of all tall students of your class

(v) collection of all clever students of your school

(vi) collection of all rich people of Bangalore

(vii) collection of some multiples of 5 (viii) collection of all prime numbers

(ix) collection of all even integers which lie between -5 and 15

(x) collection of all good cricket players of India

(xi) collection of three youngest students in your class

(xii) collection of three healthy students of your class