Which of the following are sets? Justify your answer. (a) The collection of all the days in a week beginning with the letter "T".

(b) The collection of all difficult questions in the chapther on sets.

(c) The collection of girls in your class.

(d) The collection of all vers in India.

(e) The collection of all active teachers in the school

(f) The collection of all integers more than 3.

(g) The collection of all beautiful lower in the park. the chapter on sets